adv. 25B6; adverb
he smiled happily : CONTENTEDLY, cheerfully, cheerily, merrily, delightedly, joyfully, joyously, gaily, gleefully.
I will happily do as you ask : GLADLY, willingly, readily, freely, cheerfully, ungrudgingly, with pleasure; archaic fain.
happily, we are living in enlightened times : FORTUNATELY, luckily, thankfully, mercifully, by good luck, by good fortune, as luck would have it; thank goodness, thank God, thank heavens, thank the stars.