from The American Heritage® Dictionary of the English Language, 4th Edition
- transitive v. To fail to excite, stimulate, or impress: "He is just as entitled to be underwhelmed by the prospect of reigning over a fourth-class nation as the rest of us are by the prospect of living in it” ( Peter Jay).
from Wiktionary, Creative Commons Attribution/Share-Alike License
- v. To fail to impress; to perform disappointingly.
from the GNU version of the Collaborative International Dictionary of English
- transitive v. To interest less than anticipated; to be dull to (a person).
under- + (over)whelm.(American Heritage® Dictionary of the English Language, Fourth Edition)