Main Entry: ¹on·ly

Pronunciation: \ˈōn-lē\

Function: adjective

Etymology: Middle English, from Old English ānlīc, from ān one — more at one

Date: before 12th century

1 : unquestionably the best : peerless
2 a : alone in a class or category : sole <the only one left> <the only known species> b : having no brother or sister <an only child>
3 : few <one of the only areas not yet explored>