Entry 1 sense Webster, 1913 Pyrena /pĭr-ēn'-ə/ · Py·re·na · IPA /paɪˈɹiːnə/ 01 n. A nutlet resembling a seed, or the kernel of a drupe. pl. Pyrenæ ((#)) 1. A nutlet resembling a seed, or the kernel of a drupe.(Bot.)