To elate is to fill with happiness. If you are elated, you are thrilled. You are walking on air.
Elate sounds a bit like inflate. Although the words are not related, if you elate someone the feeling is probably a bit like inflating them — filling them with happiness, making them feel as though they're floating above the ground. Not surprisingly, the word's original sixteenth century meaning was "to physically lift or raise up."
v fill with high spirits; fill with optimism
cast down, deject, demoralise, demoralize, depress, dismay, dispirit, get down
lower someone's spirits; make downhearted
make blessedly happy
make proud or conceited
beatify, exalt, exhilarate, inebriate, thrill, tickle pink
fill with sublime emotion