ranula
Medical term for a mucous cyst under the tongue, resembling a frog's belly. Used in clinical contexts.
I had a ranula removed at the oral surgery department.
From 蝦蟇 (がま, 'toad') + 腫 (しゅ, 'swelling, tumor'), so called because the swelling resembles a toad's puffed throat. The exact historical origin is uncertain.