peraja

1. Croat. (of fish) fin
   Ajkula je pokazala peraju iznad vode. — The shark showed its fin above the water.
2. Croat. (for swimming) flipper; swim fin
   Ponesi peraje i masku na more. — Take flippers and a mask to the seaside.

In Serbia the neuter form peraje (gen. peraja, pl. peraja) is usual: leđno peraje, ajkulino peraje; the feminine peraja is more typical of Croatian usage. Swim fins are usually referred to in the plural: peraja.