Hi last-rebel - it is not a stupid question. The lingo of music is confusing because there are multiple words for the same thing.
A semitone is one-half step - that would be one fret.
A whole step is two half steps - that would be two frets.
Now, just to further delight your curiosity here are some other terms for musical intervals:
Root = tonic = the starting note of a scale or chord
b2 = flatted second = 1 half step above the root
2 = second = 2 half steps above root
b3 = flatted third = 3 half steps above root
3 = third = 4 half steps above root
4 = fourth = 5 half steps above root
b5 = flatted fifth = 6 half steps above root
5 = fifth = 7 half steps above root
b6 = flatted sixth = 8 half steps above root
6 = sixth = 9 half steps above root
b7 = flatted seventh = 10 half steps above root
7 = seventh = 11 half steps above root
octave = 12 half steps above root
"That darn Pythagorean Comma thing keeps messing me up!"
[url]http://en.wikipedia.org/wiki/Pythagorean_comma[/url]