1. Omentum — de Vaan
Omentum "fatty membrane of caul, covering the intestines' [n. o] (Cat.+) It. cognates: U. umen [acc.sg.], umne [abl.sg.] 'ointment' < *omben < *ongwen-, I see no semantic support for WH's hypothesis that omentum is derived from the verb -ud 'to put on/off. Also, *owe-mento- would phonetically yield *umentumy whence o- could only arise by restoration of *cw-; but there was no word to restore this sequence from. EM … — [de Vaan, s.v. Omentum, p. 442]