good (adj.) Look up good at Dictionary.com
Old English god (with a long "o") "virtuous; desirable; valid; considerable," probably originally "having the right or desirable quality," from Proto-Germanic *gothaz (cognates: Old Norse goðr, Dutch goed, Old High German guot, German gut, Gothic goþs), originally "fit, adequate, belonging together," from PIE root *ghedh- "to unite, be associated, suitable" (cognates: Old Church Slavonic godu "pleasing time," Russian godnyi "fit, suitable," Old English gædrian "to gather, to take up together"). As an expression of satisfaction, from early 15c.; of children, "well-behaved," by 1690s.

Irregular comparatives (better, best) reflect a widespread pattern, as in Latin bonus, melior, optimus. Good-for-nothing is from 1711. Good looking is attested from 1780 (good looks by c.1800). Good sport, of persons, is from 1906; good to go is attested from 1989. The good book "the Bible" attested from 1801, originally in missionary literature describing the language of conversion efforts in American Indian tribes.
Why then, can one desire too much of a good thing. ["As You Like It"]
Phrase for good "finally, permanently" attested from 1711, a shortening of for good and all (16c.). Middle English had for good ne ylle (early 15c.) "for good nor ill," thus "under any circumstance."
good (n.) Look up good at Dictionary.com
Old English gōd "that which is good, goodness; advantage, benefit; gift; virtue; property;" from good (adj.).