Spelling Question

[Vorpal_Blade]

Is there a rule or pattern regarding –er versus –or endings? As an example: “creator” versus “creater”. Or dictator vs. dictater? My spellcheck doesn’t like dictater (or creater) but what, then, do you call a person who dictates and why?

tl;dr: When do you use 'er and when do you use -or?

[Exapno_Mapcase]

No rule, just quirks of history.

http://english.stackexchange.com/questions/4733/whats-the-rule-for-adding-er-vs-or-when-nouning-a-verb

Generally speaking, -er is much more common in English (which should come as no surprise since it has deep Germanic roots, see the link) and can be easily attached to any English verb to form the corresponding noun (drive — driver, run — runner, drink — drinker, etc.).

The suffix -or, on the other hand, comes from Latin, and is used much more seldom, basically where Latin would do it. Just try building the words drivor, runnor or drinkor, and see for yourself. In fact, Wiktionary lists only a handful of terms that were derived using this suffix, such as actor, author and sculptor, and goes on to provide the following usage notes:

English generally appends this suffix where Latin would do it—to the root of a Latin-type perfect passive participle. For other words, English tends to use the suffix -er. Occasionally both are used (computer vs. computor).

[Hari_Seldon]

On the other hand, we have “adviser” and “advisor”, although the latter is rejected by my spell checker. They do differ slightly in meaning, the latter more akin to supervisor. “Advise”, of course, has a Latin origin. I do not think there is any rule. Certainly I don’t know any.

[Exapno_Mapcase]

I like to use advisor myself, and it is given as an alternate spelling in dictionaries. Why spell checkers don’t like it is a mystery to me, but mine just flagged it. For the last time.

It’s a good example of why there is no hard and fast rule. Language happens.