When Y-H-B commented on a woman server’s behavior in addressing him recently while he waited to be served at his Stammtisch at The Dorset Inn, he used the word “ebullient,” but the woman’s look of incomprehension revealed that the word was unknown to her, so he switched to “effervescent.” The server, nota bene, was an elementary school teacher who should have known better, but such is the state of the knowledge of the English language among its American practitioners that often useful words are not within their ken.
In any event, here is what ‘ebullient’ means according to the OED Online:
1. That boils; boiling; agitated, as if boiling.
2a. Of the humours of the body: Agitated, hot, effervescent.
b. Of drugs and diseases: Causing heat and agitation.
3. figurative. Of energy, feelings, influences: Gushing forth like boiling water;bubbling over,   overflowing, enthusiastic. Constr. with.