Laudator Temporis Acti

Nausea originally meant seasickness. From an etymological standpoint it's shipsickness, from Greek naus = ship.

There are pitfalls associated with the word nausea and its derivatives. Adjectival forms in English are nauseated, nauseating, and nauseous. Concerning nauseous versus nauseated, the 4th edition of Strunk and White's Elements of Style (2000) says:

The first means "sickening to contemplate"; the second means "sick at the stomach." Do not, therefore, say, "I feel nauseous," unless you are sure you have that effect on others.

In other words, Strunk and White would restrict nauseous to mean nauseating (causing nausea), not nauseated (feeling nausea). The distinction is disappearing. Merriam-Webster's Concise Dictionary of English Usage (2000) cites numerous examples of nauseous meaning nauseated, to which may be added this sentence by John Grisham, from his novel The Street Lawyer (1998), chapter 4:

But the smell of fresh paint made me nauseous.

Purists would say that the smell of fresh paint was nauseous, and that the smell made the narrator nauseated. If you're in doubt, the simplest solution is to banish nauseous and use either nauseated or nauseating, as the context demands.

In Latin, the verb nauseo likewise can mean both be seasick and cause disgust, although the former meaning is the more common.

A second pitfall is the Latin phrase ad nauseam, frequently misspelled ad nauseum. The preposition ad takes the accusative case, and the accusative singular of nausea is nauseam, not nauseum. Google statistics are unreliable -- I see 162,000 occurrences of ad nauseam, 182,000 of ad nauseum, which would lead me to conclude that the erroneous form is winning out over the correct form. But when I click on some of the ad nauseum links, I find only ad nauseam. Apparently Google software is conflating the two. I find this nauseating.