apperceive v.

word-forming element expressing direction toward or in addition to, from Latin ad "to, toward" in space or time; "with regard to, in relation to," as a prefix, sometimes merely emphatic, from PIE root *ad- "to, near, at."

Simplified to a- before sc-, sp- and st-; modified to ac- before many consonants and then re-spelled af-, ag-, al-, etc., in conformity with the following consonant (as in affection, aggression). Also compare ap- (1).

In Old French, reduced to a- in all cases (an evolution already underway in Merovingian Latin), but French refashioned its written forms on the Latin model in 14c., and English did likewise 15c. in words it had picked up from Old French. In many cases pronunciation followed the shift.

Over-correction at the end of the Middle Ages in French and then English "restored" the -d- or a doubled consonant to some words that never had it (accursed, afford). The process went further in England than in France (where the vernacular sometimes resisted the pedantic), resulting in English adjourn, advance, address, advertisement (Modern French ajourner, avancer, adresser, avertissement). In modern word-formation sometimes ad- and ab- are regarded as opposites, but this was not in classical Latin.

c. 1300, perceiven, "become aware of, gain knowledge of," especially "to come to know by direct experience," via Anglo-French parceif, Old North French *perceivre (Old French perçoivre) "perceive, notice, see; recognize, understand," from Latin percipere "obtain, gather, seize entirely, take possession of," also, figuratively, "to grasp with the mind, learn, comprehend," literally "to take entirely," from per "thoroughly" (see per) + capere "to grasp, take," from PIE root *kap- "to grasp."

Replaced Old English ongietan. Both the Latin senses were in Old French, though English uses the word almost always in the metaphorical sense. Related: Perceived; perceiving.

1753, "self-consciousness," from French aperception (17c.), from Latin apperceptionem, from ad "to" (see ad-) + perceptionem (nominative perceptio) "perception, apprehension, a taking," noun of action from past-participle stem of percipere "to perceive" (see perceive).

The meaning "act of the mind by which it becomes conscious of its ideas as its own (1876) is from German Apperzeption, coined by mathematician and philosopher Gottfried Wilhelm Leibniz (1646-1716) as noun corresponding to French apercevoir "perceive, notice, become aware of" on analogy of Perzeption/percevoir.