leptocardian🔊adjEtymology From Leptocardii + -an.1Biology, Natural sciences, Zoology Dated Of or relating to the Leptocardii (formerly Leptocardia).
leptocardian🔊nounEtymology From Leptocardii + -an.1Biology, Natural sciences, Zoology Dated A lancelet (one of the Leptocardii).