I have two fairly old unabridged dictionaries, one of which gets looked at perhaps once a week. The other one, at the other end of the house, is just not too convenient.

Several desktop dictionaries, almost never looked at. I tend to find that if I don't know a word it's probably not in the abridged.

Two medical dictionaries, Dorland's and Taber's, which I occasionally need to check, especially Dorland's.

I have a moderately current version of The Physician's Desk Reference,
about the size of an unabridged dictionary. I don't look at that more than perhaps once or at most twice a year. I think. My wife, on the other hand, is extremely interested in health, and often wants to check on various medications.

The reference book that I personally use most is ORIGINS, A Short Etymological Dictionary of Modern English, by Eric Partridge, the 1983 version.

I used to consult any or all of these much more than I do these days, because of the ease of consulting various sources via Google, which I do a lot.

Dave Oesterreich