Entry 1 sense Webster, 1913 Spinescent /spī-nĕs′ənt/ · Spi·nes·cent · IPA /spaɪ̯ˈnɛs.ənt/ 01 a. Becoming hard and thorny; tapering gradually to a rigid, leafless point; armed with spines. 1. Becoming hard and thorny; tapering gradually to a rigid, leafless point; armed with spines.(Bot.)