The Collaborative International Dictionary of English v.0.48:
Pseudo-bulb \Pseu"do-bulb`\, n. [Pseudo- + bulb.] (Bot.) An a["e]rial corm, or thickened stem, as of some epiphytic orchidaceous plants. [1913 Webster]WordNet (r) 3.0 (2006):
pseudobulb n 1: a solid bulblike enlargement of the stem of some orchids