Meaning

adjective having or demonstrating ability to recognize or draw fine distinctions

adjective intense or sharp

adjective very good

originEtymology tree English keen Proto-Indo-European *-yósder. Proto-Italic *-āzijos Latin -āriusnom. Latin -āriusbor. Proto-Germanic *-ārijaz Proto-West Germanic *-ārī Old English -ere Middle English -ere English -er English keener From keen (“lament”, verb) + -er (“one who does”).

Etymology from Wiktionary, CC BY-SA 3.0