Catch on and Sponge up

Catch on verb - Understand, usually after some initial difficulty.

Sponge up and catch on are semantically related. In some cases you can use "Sponge up" instead a verb "Catch on".

Sponge up verb - Absorb as if with a sponge.

Catch on and sponge up are semantically related. Sometimes you can use "Catch on" instead a verb "Sponge up".