-cide

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.

"the continual falling of drops," 1620s, from Latin stillicidium "a dripping, falling of drops, a liquid which falls in drops" from stilla "a drop" (see distill (v.)) + cadere "to fall" (from PIE root *kad- "to fall").

In Roman law, the dropping of rainwater from one's roof on another's roof or land, as a right or nuisance, and the word was also used in this sense in Scottish law from 17c. Related: Stillicidious.

Stiricide, a 17c. dictionary word, seems to have meant more or less "the dropping of icicles from a house," also with cadere, and Latin stiria "icicle" (itself in English in various technical senses from 17c.), which sometimes is connected to the PIE root of stiff (adj.), but de Vaan suggests a connection of stiria "icicle"/stilla "dripping."