pp1d05 afficere, affectio NOT affectus 
Forms affectus est, affectus consideratur, affectum fuit, NOT affectus-noun. 
Meaning

affect some thing (res), Precisely: change of state due to external cause, an impact. Elwes renders "modification" for "affectio", this site bluntly uses the English word affection. Both thought-modi and extended modi are affections of substance (see below quote of {1d05}). Technically specified for corporeal things (res extensa) starting {2a2.1 corpora moventur quiescunt}  in the sense of cartesian movement and collision of  particles. Every kind of extended thing can get affected. When it is a human body the affectio is called an affectus ("emotion") " ... Per affectum intelligo corporis affectiones  ... .", NOT a pleonasm: affectio is among the concepts defining affectus, the affections of the human body. 
N.B.: affectus est, affectus consideratur, affectum fuit etc, are forms of afficere, but hence substrings can be identical to affectus (emotion). Everywhere, terms are linked to their local meaning.

Subsets (kinds) affectus-corpus, imago, vestigium (affections of the human body), and affectus-mens
Occurrence [geomap]
{1d05 modus}                                                                                         ... two highly technical and complicated strings expressing the same meaning ...
 ... the modifications [Lat: affectiones] of substance, or that which exists in, and is conceived through, something other than itself.  ... substantiae affectiones sive  [mng-eqv] id quod in alio est, per quod etiam concipitur.
{1p04 distinctae attributorum vel affectionum}                     ... "substances" means the same as "their attributes and affectiones" ...
 ...  the substances, or, in other words  ...  their attributes and modifications ...  ...  substantias sive  [prf-eqv] quod idem est  ... earum attributa earumque affectiones ...
{3d03 affectus}                                                                                     ... affectiones corporis are one special type of affectio, called affectus ...
 ... By emotion I mean the modifications [Lat: affectiones] of the body ...  ... Per affectum intelligo corporis affectiones ...  
{3p17 odio simul amabimus}                                                          ... also in {5p17} {5p17c} " ... affectus afficere ... " NOT a pleonasm!  ... (See quote above)
 ... thing which normally affects us with the emotion of pain ...  ... rem quae nos tristitiae affectu afficere solet ...

Equivalence claims involving afficere, affectio
{1d05} [notes] 1. mode 1. modifications [Lat: affectiones] of substance 3. that which exists in, and is conceived through, something other than itself. 1. modum 2. substantiae affectiones 3. id quod in alio est, per quod etiam concipitur.
{1p25c} 1. Individual things 2. modifications [Lat: affectiones] of the attributes of God 3. modes by which the attributes of God are expressed in a fixed and definite manner. 1. Res particulares 2. Dei attributorum affectiones 3. modi quibus Dei attributa certo et determinato modo exprimuntur.
{2p09} [about ideas as causes
1. Another idea 2. God in as far he is considered affected by another idea
[De ideis quatenus causis] 1. alia idea 2. Deus quatenus alia idea affectus consideratur
{2p19} [About the human body] 1. in so far as he is regarded as affected by another idea of a particular thing actually existing 2. inasmuch as the human body stands in need of very many bodies  [De corpori humane] 1. quatenus alia rei singularis idea affectus consideratur 2. quatenus plurimis corporibus indiget
{2p19} [About God = natura-sense 2 = substance and the human mind] 1. God has the idea of the human body 2. [God = natura-sense 2 = substance] knows the human body, in so far as he is affected by very many other ideas, and not in so far as he constitutes the nature of the human mind [De deo et menti humane] 1. [Deus] ideam corporis humani habet 2. [Deus] corpus humanum cognoscit quatenus plurimis aliis ideis affectus est et non quatenus naturam humanae mentis co constituit
{2p25} 1. an adequate knowledge of the external body is not in God, in so far as he has the idea of the modification [Lat: affectiones] of the human body 2. the idea of the modification [Lat: affectiones] of the human body does not involve an adequate knowledge of the external body. 1. corporis externi adaequata cognitio in Deo non est quatenus ideam affectionis humani corporis habet 2. idea affectionis corporis humani adaequatam corporis externi cognitionem non involvit.
{2p25} 1. an adequate knowledge of the external body is not in God, in so far as he has the idea of the modification [Lat: affectiones] of the human body 2. the idea of the modification [Lat: affectiones] of the human body does not involve an adequate knowledge of the external body. 1. corporis externi adaequata cognitio in Deo non est quatenus ideam affectionis humani corporis habet 2. idea affectionis corporis humani adaequatam corporis externi cognitionem non involvit.
{2p29} [About the ideas of affections of the human body] 1. do not involve an adequate knowledge of the said body 2. does not adequately express its nature 3. they do not adequately agree with the nature of the mind 4. the ideas of such ideas do not adequately express the nature of the human mind 5. [the ideas of such ideas] do not involve an adequate knowledge thereof. [De ideis affectionis corporis humani] 1. adaequatam ipsius corporis cognitionem non involvit 2. ejus naturam adaequate non exprimit 3. cum natura mentis non convenit adaequate 4. hujus ideae ideam adaequate humanae mentis naturam non exprimit 5. adaequatam ejus cognitionem non involvit.
{3d03} [notes] [About the human body] 1. [corporeal BH] emotion 2. the affections of the body, whereby the active power of the said body is increased or diminished, aided or constrained [De corpori humani] 1. affectum [affectus-corpus] 2. corporis affectiones quibus ipsius corporis agendi potentia augetur vel [excl non-exh] minuitur, juvatur vel [excl non-exh] coercetur
{3d03} [notes] [About the human mind] 1. [mental BH] emotion  2. the ideas of the affections of the body, whereby the active power of the said body is increased or diminished, aided or constrained
[De menti humani] 1. affectum [affectus-mens] 2.  ideas corporis affection[um] quibus ipsius corporis agendi potentia augetur vel [excl non-exh] minuitur, juvatur vel [excl non-exh] coercetur
{3d03} [notes] [About mental and corporeal emotions] 1. Action 2. An affection of ours of which we are the adequate cause. [De affectuum-mentis et affectuum-corpus] 1. actio 2. affectio nostra adaequate causata nobis
{3d03} [notes] [About mental and corporeal emotions] 1. Passion 2. An affection of ours of which we are not the adequate cause. [De affectuum-mentis et affectuum-corpus] 1. passionem 2. affectio nostra non adaequate causata nobis
{3p30} [About humans] 1. be affected by pleasure, accompanied by the idea of oneself as cause 2. regard oneself with pleasure. [De hominum] 1. laetitia concomitante idea sui tanquam causa afficietur 2. se ipsum cum laetitia contemplabitur
{3p40} 1. affected by pain associated with the idea of the one we hate 2. hate someone 1. tristitia afficietur concomitante idea ejus qui ipsum odio habet 2. eundem odio habebit.
{3p56} 1. imagine 2. be affected by an emotion, which involves the nature of our own body, and the nature of an external body. 1. imaginamur 2. afficimur affectu qui naturam nostri corporis et naturam corporis externi involvit.
{3p56} 1. desire 2. each man's essence or nature, in so far as it is conceived as determined to a particular action by any given modification [Lat: affectiones] of itself 1. cupiditas 2. ipsa uniuscujusque essentia seu [mng eqv] natura quatenus ex data quacunque ejus constitutione determinata concipitur ad aliquid agendum
{3de01} [notes] 1. Desire 2. the actual essence of man, in so far as it is conceived, as determined to a particular activity by some given modification [Lat: affectiones] of itself. 1.Cupiditas 2. ipsa hominis essentia quatenus ex data quacunque ejus affectione determinata concipitur ad aliquid agendum
{3de23} 1. Envy 2. hatred, in so far as it induces a man to be pained by another's good fortune, and to rejoice in another's evil fortune. 1. Invidia 2. odium quatenus hominem ita afficit ut ex alterius felicitate contristetur et contra ut ex alterius malo gaudeat
{3de34} 1. Thankfulness 2. Gratitude 3. the desire or zeal springing from love, whereby we endeavour to benefit him, who with similar feelings of love has conferred a benefit on us. 1. Gratia 2. gratitudo 3. cupiditas seu [non-excl non-exh] amoris studium quo ei benefacere conamur qui in nos pari amoris affectu beneficium contulit.
{4p08} 1. emotion 2. idea about an affection of the body 1. affectu 2. idea corporis affectionis
{5p01} 1. affections of the body 2. the images of things 1. corporis affectiones 2. rerum imagines