Oncostoma
on-KOS-toh-muh
Genus
hooked or swollen bill
Literally: hook (or swelling) mouth
| Part | Meaning | Language | Note |
|---|---|---|---|
| onco- | a mass; a tubercle; a hook, barb | Greek (onc, -o, =us) | combining form; the -o- is the standard Greek combining vowel built into the entry |
| stoma | a mouth | Greek (stom, =a, -ato, -o) | standalone =a form; serves as the head noun of the compound; Greek neuter, giving the genus a neuter grammatical gender |
A pure Greek compound noun: the modifier onco- (hook / swelling) precedes the head noun stoma (mouth). The construction is a determinative compound — the mouth is characterised by being hooked or swollen. As a genus name it is treated as Latin neuter (-a ending). The word is used without a species epithet here, so no agreement question arises; any epithet must be neuter. Oncostoma is a real genus of tyrant-flycatchers (Aves: Tyrannidae) diagnosed by their distinctively curved upper mandible.
Pronunciation
- on-KOS-toh-muh Four syllables: on-cos-to-ma. Penult 'to' has a short vowel (o) followed by only one consonant (m), so no penult-stress rule is triggered. Stress therefore falls on the ANTEPENULT 'cos'. The antepenult vowel o is short (it is followed by the consonant cluster st, not by a single consonant then vowel meeting the lengthening condition).
Other readings
onco- could be read as 'mass / tumor' rather than 'hook', giving 'swollen mouth / tumid bill'; both meanings come from the same Greek root oncos and are biologically plausible for a bird with an enlarged bill.
The genus Oncostoma was erected for small tyrant-flycatchers of Central and South America; the name refers to the distinctively hooked or swollen bill tip, reflecting onco- = hook/barb. Both onc and onco appear as separate dictionary entries (onc, -o, =us and onco; =oncus) with overlapping meanings (hook, barb, mass, swelling, tumor); the hook/barb sense is most appropriate for a bird bill. stoma here is used in its basic anatomical sense 'mouth / oral opening', as in common scientific compounds (stomatology, Gnathostoma, Macrostoma, etc.).