Singular
Middle English (in the sense ‘solitary, single’, also ‘beyond the average’): from Old French singuler, from Latin singularis, from singulus (see single).
wiktionary
From Middle English singuler, borrowed from Old French, from Latin singulāris(“alone of its kind”), from Latin singulus(“single”).
etymonline
singular (adj.)
mid-14c., "alone, apart; being a unit; special, unsurpassed," from Old French singuler "personal particular; distinctive; singular in number" (12c., Modern French singulier) or directly from Latin singularis "single, solitary, one by one, one at a time; peculiar, remarkable," from singulus "one, one to each, individual, separate" (see single (adj.)). Meaning "remarkably good, unusual, rare, separated from others (by excellence), uncommon" is from c. 1400 in English; this also was a common meaning of Latin singularis.