I would say that you've got your definitions right, Marty, but I would disagree with your example. The vowel sound in rain is actually a diphthong, where the movement is between the vowels in bet and bit. A better example would be head , where there is the pure vowel (aka monophthong) heard in bet (except in Scotland, where I believe it is pronounced more like heed).

Bingley

Bingley