(There may be other examples in this vein, but these two stuck out to me recently.)

We call someone who practices astrology an astrologer. We call someone who practices geology a geologist. It seems odd that the subjects they practice (astrology, geology) are both created from Latin roots in the same way, but the titles take different forms.

There are some results searching for "astrologist" and "geologer", but they are far less prevalent or noted to be dated usages. (ngram viewer: Astrologer vs. Astrologist, Geologist vs. Geologer)

Why the different endings?

  • 4
    There are also -logue formations, though they are much rarer than the other two. Ideologue is the only one I can think of off the top of my head that's reasonably common (and ideologist was, perhaps surprisingly, more common until around 1980 according to Ngrams), though astrologue is also attested (later than astrologer, but earlier than astrologist) according to the OED. And then there's astrologian (comparable to theologian), which is almost as early as astrologer. My best bet at a reason is that people (especially English people) are random and bonkers. Sep 13 '16 at 15:37
  • @JanusBahsJacquet That was my suspicion too... but I figure if anyone might have the answer it would be on this site :) Thanks for the extra info, more words to puzzle over!
    – user812786
    Sep 13 '16 at 18:46
  • I suspect that it depends whether the word went Latin/Greek -> French -> English (-oger) vs. Latin/Greek -> English (-ist), but I don't have any data to back that up.
    – John Feltz
    Sep 17 '16 at 23:52

Firstly the etymology of the two suffixes.


word-forming element meaning "one who does or makes," also used to indicate adherence to a certain doctrine or custom, from French -iste and directly from Latin -ista (source also of Spanish, Portuguese, Italian -ista), from Greek agent-noun ending -istes, which is from -is-, ending of the stem of verbs in -izein, + agential suffix -tes. - Etymonline

-er (1)

English agent noun ending, corresponding to Latin -or. In native words it represents Old English -ere (Old Northumbrian also -are) "man who has to do with," from Proto-Germanic *-ari (cognates: German -er, Swedish -are, Danish -ere), from Proto-Germanic *-arjoz. Some believe this root is identical with, and perhaps a borrowing of, Latin -arius (see -ary).

Generally used with native Germanic words. In words of Latin origin, verbs derived from past participle stems of Latin ones (including most verbs in -ate) usually take the Latin ending -or, as do Latin verbs that passed through French (such as governor); but there are many exceptions (eraser, laborer, promoter, deserter; sailor, bachelor), some of which were conformed from Latin to English in late Middle English. - Etymonline

Thus, the -er suffix is from Germanic origin, while -ist is from Latin.

In the specific case of the astrologer there might be some more information from the following excerpt to consider.

astrologer (n.)

late 14c., from astrology + -er (1). Drove out French import astrologein, which, had it survived, probably would have yielded *astrologian, as in Chaucer's "The wise Astrologen." Earliest recorded reference is to roosters as announcers of sunrise. - Etymonline

The first astrologers were animals, if we consider the two dictionary entries from ODO regarding the two suffixes, -er and -ist, we can see that -ist is constricted to people, while -er explicitly applies to people or things. Since -ist is reserved for humans the astrologist had no chance while the job was done by an animal.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.