The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
gwer-2
DEFINITION:
To favor. Oldest form *gwer2-.1. Suffixed zero-grade form *gw-to-.grace, grateful, gratify, gratis, gratitude, gratuitous, gratuity; agree, congratulate, disgrace, ingrate, ingratiate, maugre, from Latin grtus, pleasing, beloved, agreeable, favorable, thankful, with related suffixed forms *gw-ti-,*gw-t--,*gw-t-olo-.2. Probably compound zero-grade form *gw-dh()-o-, he who makes praises (*-dh()-, to do; see dh-). bard1, from Welsh bardd and Scottish and Irish Gaelic bard, bard, from Celtic bardo-, bard. (Pokorny 4. ger()- 478.)