Roundhead is a synonym of longfin.
As nouns the difference between roundhead and longfin
is that roundhead is a roundhead screw, one with a domed head while longfin is any member of the family plesiopidae of elongated perciform fish.
As an adjective roundhead
is having a dome-shaped head.
longfin
English
Noun
(
en noun)
Any member of the family Plesiopidae of elongated perciform fish.
Synonyms
* roundhead
* spiny basslet