[odnes_lex]

As a Greek, I feel the need to protest the corruption of the word cleistophobia (kleisto = closed) into claustrophobia. Claus- sounds like the root of "to cry" (e.g. clausigelos = crying laughter), so a Greek reading claustrophobia thinks of people who are afraid of crying (though the proper rendering of a word composite with that meaning would be klauthmophobia).

[mr_toad]

Claustro- comes from Latin Claustrum, which shares the same root as the Greek word. Claustrophobia wasn’t a word in Latin or Greek though, it’s a modern hybrid.

[kgeist]

According to the etymological dictionary:

>From Latin claustrum (“a shut-in place”), from claudō (“I shut, close; I imprison, confine”) + -phobia. First attested in the British Medical Journal

So it's not a corruption. It's a neologism.