- the unsegmented, preoral portion of the head of certain lower invertebrates.
Origin of prostomium
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for prostomium
Prostomium: The region in front of the mouth; the preoral part of the head.The Sea-beach at Ebb-tide
Augusta Foote Arnold
Prostomium wider than long, deeply bilobed, the median tentacle inserted deeply in the intervening incision.
Prostomium shortly subcordate, well rounded in front, incurved caudally.
Prostomium of usual general form; consisting of fourteen or fifteen rings.
Prostomium with a lateral process or horn on each side in front, notched in front at middle.
- the lobe at the head end of earthworms and other annelids: bears tentacles, palps, etc, or forms part of a sucker or proboscis
via New Latin from Greek prostomion mouth
Word Origin and History for prostomium
Online Etymology Dictionary, © 2010 Douglas Harper