What is meant when we say that alkanes are saturated?

Question

Carbon has four bonds. When all the bonds are occupied with hydrogen atoms(no double or triple bonds), the molecule is said to be saturated.
CH4 is saturataed.

CH3CH3 or C2H6 is saturated. There is a C-C bond with the other three bonds on each carbon occupied by a hydrogen atom.

H2C=CH2 is ethene. This is an alkene and it is unsaturated.

HC(triple bond)CH [I can't draw a triple bond with this keyboard.] This is ethyne. It is unsaturated also, just more unsaturated than ethene. This is an alkyne. Just remember that the ending -ane means saturated, the ending -ene means unsaturated (an alkene) and the ending -yne means unsaturated (an alkyne). This may be more than you ever wanted to know about the stuff but the extra infor is on me. I hope this helps.