The Collaborative International Dictionary of English v.0.48:
Happy \Hap"py\ (h[a^]p"p[y^]), a. [Compar. Happier
(-p[i^]*[~e]r); superl. Happiest.] [From Hap chance.]
1. Favored by hap, luck, or fortune; lucky; fortunate;
successful; prosperous; satisfying desire; as, a happy
expedient; a happy effort; a happy venture; a happy omen.
Chymists have been more happy in finding experiments
than the causes of them. --Boyle.
2. Experiencing the effect of favorable fortune; having the
feeling arising from the consciousness of well-being or of
enjoyment; enjoying good of any kind, as peace,
tranquillity, comfort; contented; joyous; as, happy hours,
Happy is that people, whose God is the Lord. --Ps.
The learned is happy Nature to explore,
The fool is happy that he knows no more. --Pope.
3. Dexterous; ready; apt; felicitous.
One gentleman is happy at a reply, another excels in
a in a rejoinder. --Swift.
Happy family, a collection of animals of different and
hostile propensities living peaceably together in one
cage. Used ironically of conventional alliances of persons
who are in fact mutually repugnant.
Happy-go-lucky, trusting to hap or luck; improvident;
easy-going. "Happy-go-lucky carelessness." --W. Black.