c. 1300, deinte, "delightful, pleasing" (late 12c. as a surname), from dainty (n.); see below. Meaning evolved in Middle English to "choice, excellent" (late 14c.) to "delicately pretty, exhibiting exquisite taste or skill" (c. 1400). Sense of "fastidious, affectedly fine, weak, effeminate" is from 1570s. Related: Daintiness.
The noun is Middle English deinte "regard, affection" (mid-13c.), from c. 1300 as "excellence, elegance;" also "a luxury, a precious thing, fine food or drink;" from Anglo-French deinte, Old French deintie (12c.) "price, value," also "delicacy, pleasure," from Latin dignitatem (nominative dignitas) "greatness, rank, worthiness, worth, beauty," from dignus "worthy, proper, fitting," from PIE *dek-no-, from root *dek- "to take, accept."