Entry 2 senses · 2 variants Webster, 1913 Yesternight · Yes·ter·night · IPA /ˈjɛstə(ɹ)naɪt/ n. adv. 01 n. The last night; the night last past. 1. The last night; the night last past. 02 adv. On the last night. 1. On the last night.