collide v.

word-forming element usually meaning "with, together," from Latin com, archaic form of classical Latin cum "together, together with, in combination," from PIE *kom- "beside, near, by, with" (compare Old English ge-, German ge-). The prefix in Latin sometimes was used as an intensive.

Before vowels and aspirates, it is reduced to co-; before -g-, it is assimilated to cog- or con-; before -l-, assimilated to col-; before -r-, assimilated to cor-; before -c-, -d-, -j-, -n-, -q-, -s-, -t-, and -v-, it is assimilated to con-, which was so frequent that it often was used as the normal form.

late 14c., adquisicioun, "act of obtaining," from Old French acquisicion "purchase, acquirement" (13c., Modern French acquisition) or directly from Latin acquisitionem (nominative acquisitio), noun of action from past-participle stem of acquirere "get in addition, accumulate," from ad "to," here perhaps emphatic (see ad-), + quaerere "to seek to obtain" (see query (v.)).

The meaning "thing obtained" is from late 15c. The vowel change of -ae- to -i- in Latin is due to a phonetic rule in that language involving unaccented syllables in compounds.