The headword as transmitted is a participle (masculine nominative singular), as if from o)gkulo/omai, apparently a variant of o)gku/llomai (for which see omicron 24). Same entry elsewhere: see the references at Photius omicron22 Theodoridis, where however the editor follows Dindorf in holding that the correct form of this participle is o)gkullo/menos. Evidently quoted from somewhere, in whatever form.
Erotian (Collection of Hippocratic Words) reports from Hippocrates the phrase o)gkulwme/nh koili/a "swollen belly".