contrivance n.

early 14c., controve, contreve, "to invent, devise, plan;" late 14c., "to manage by a plan or scheme," from Old French controver (Modern French controuver) "to find out, contrive, imagine," from Late Latin contropare "to compare" (via a figure of speech), from an assimilated form of Latin com "with, together" (see con-) + tropus "song, musical mode," from Greek tropos "figure of speech" (from PIE root *trep- "to turn").

Sense evolution (in French) was from "invent with ingenuity" to "invent falsely." Spelling in English was altered by the same unexplained 15c. sound change that also affected briar, friar, choir. Related: Contrived; contriving.

word-forming element attached to verbs to form abstract nouns of process or fact (convergence from converge), or of state or quality (absence from absent); ultimately from Latin -antia and -entia, which depended on the vowel in the stem word, from PIE *-nt-, adjectival suffix.

Latin present-participle endings for verbs stems in -a- were distinguished from those in -i- and -e-. Hence Modern English protestant, opponent, obedient from Latin protestare, opponere, obedire.

As Old French evolved from Latin, these were leveled to -ance, but later French borrowings from Latin (some of them subsequently passed to English) used the appropriate Latin form of the ending, as did words borrowed by English directly from Latin (diligence,absence).

English thus inherited a confused mass of words from French (crescent/croissant), and further confused it since c. 1500 by restoring -ence selectively in some forms of these words to conform with Latin. Thus dependant, but independence, etc.