Do you know what a galileo, a dyne, or a stigma is?

Hey, Maverick, you gave it away. They're all units of measure:

galileo Symbol: Gal ≡ 1 cm/s2 = 0,01 m/s2
dyne [French] Symbol: dyn ≡ 10-5 N
stigma ≡ 10-12m = 1 pm

I've got no idea what they measure, but they're handy little words for a limerick.

A galieo, a stigma and a dyne
Took a walk together on a line.
They wanted to settle
In a test of mettle
Who's the biggest and the broadest measure sign.