Other forms: elated; elating; elates
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."