Convertible
late Middle English (in the sense ‘interchangeable’): from Old French, from Latin convertibilis, from convertere ‘turn about’ (see convert).
wiktionary
From Old French convertible, from Late Latin convertibilis(“ interchangeable”), from Latin convertere(“to turn back, to turn over, to turn around, to turn upside down”), from con-(“ with, together”) + vertere(“to turn”), + -ibilis(“ -ible: able to”). Equivalent to convert + -ible.
etymonline
convertible (adj.)
late 14c., "interchangeable," from Old French convertible "interchangeable" (13c.) and directly from Late Latin convertibilis "changeable," from Latin convertere "to turn around; transform," from assimilated form of com "with, together" (see con-) + vertere "to turn" (from PIE root *wer- (2) "to turn, bend").
Meaning "capable of being changed in form, substance, or condition" is from 1530s. Of paper money, etc., "capable of being converted into gold of a similar amount," from 1834. The noun is recorded from 1610s; meaning "automobile with a fold-down top" is from 1916. Related: Convertibility.
