Entry 1 sense Webster, 1913 Latchkey /lăch'-kēˌ/ · Latch·key · IPA /ˈlæt͡ʃˌki/ 01 n. A key used to raise, or throw back, the latch of a door, esp. a night latch. 1. A key used to raise, or throw back, the latch of a door, esp. a night latch.