Grossly underused words

I was going to use ersatz, but Crash beat me to it. That's always been a favorite of mine.

Defenestrate is one that's always held a place in my heart but is rarely seen or heard, even when I hear of one's possessions being forcibly ejected through a window. I'm also rather fond of old euphemisms like jinkies or golly jeepers - they make me grin idiotically.

Also, ubiquitous and magnanimous - considering their definitions, you'd think they'd be used far more often.

Jam it back in, in the dark.

These aren't exactly grossly underused, since there's hardly any need or point to using them (or they're used enough) but they are a couple of my favorite words.

Floccinaucinihilipilification, a word which no longer appears in most editions of the dictionary due to its extreme lack of usage and archaic roots, is by far one of the most fun to say and spell. It means, if I remember correctly, the evaluation of something as nothing; meaningless; of little to no worth; trivial. I once used it in a conversation, accusing the poor bastard of douchebaggery (also a favorite) and general floccinaucinihilipilification in regards to my opinion of a very important topic, and he stared at me blankly like his brain had just exploded. Then he told me to spell it and I did without skipping a beat.

Pneumonoultramicroscopicsilicovolcanoconiosis, which is technically the longest word in the English language, is just a fancy medical term for black lung disease, but I love throwing that one at smokers and, far less frequently due to lack of opportunity, coal miners.

I also realized today that I love the words dongle, trepidation, and tomfoolery. Dongle is just a funny word, trepidation has always appealed to me more than its counterpart apprehension, and tomfoolery just gives such an excellent mental image of its meaning that I can't help but chuckle when I hear it.

Also, ravish - the verb, by itself. When used in context, it sounds rather sensual.

There's nowhere I can't reach.