1. To be submerged, turned-over, or covered up. Or, more commonly,
2. To be so over-taken with emotion or excitement that one feels "turned upside down" or completely engulfed.
It does NOT mean "neutral" or BETWEEN "underwhelmed" and "overwhelmed". If anything, "whelmed" means to be overwhelmed or just slightly less excited than "overwhelmed".
The dance was so whelming, I was almost overwhelmed.
Chastity: I know you can be overwhelmed, and you can be underwhelmed, but can you ever just be whelmed?
Bianca: I think you can in Europe.
~ 10 Things I Hate about You
can most commonly be used when a fact is given, intending to be interesting, but in fact is completely useless
Person 2: oh yeah?
Person 1: The average person drinks four cups of tea per week
Person 2: I am whelmed by that information