The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
gu-
DEFINITION:
To rejoice; also to have religious fear or awe. Oldest form *ge2u-, colored to *ga2u-, contracted to *gau- (before consonants) and *gw- (before vowels). 1. Suffixed extended form *gw-idh--.gaud, gaudy1, gaudy2, joy; enjoy, rejoice, from Latin gaudre, to rejoice. 2. Form (with nasal infix) *g-n-u-.ganoid, from Greek ganusthai, to rejoice. (Pokorny gu- 353.)