Executor vs. Executor Pronunciation

Question

Does anyone know why the accent of executor (as in “executioner”) is on the first syllable, whereas the accent of executor (of a will, for example) is on the second syllable?

Answer 1

(This answer uses the IPA stress marks: ˈ before the syllable with primary stress, ˌ before a syllable with secondary stress. E.g. ˌappliˈcation, with secondary stress on the first syllable and primary stress on the third.)

We can get -tor nouns from different processes.

Some of them can be analyzed as agent nouns composed of a verb plus a suffix /əɹ/ (alternatively pronounced /ə/ in accents where the consonant sound /ɹ/ is not used at the end of a syllable). In this context, -or is equivalent in meaning to -er, and these can be considered to function merely as alternative spellings of the same suffix. This suffix /ə(ɹ)/ does not trigger a shift in stress, so the stress falls in the same place as in the base verb. The verb ˈexecute is stressed on the first syllable: thus, so is the derived agent noun ˈexecut/əɹ/. (Araucaria suggested in a comment that it would be better to spell the agent noun derived from the verb ˈexecute as ˈexecuter: whichever way you spell it, it's essentially the same word.)

However, in terms of etymology, the ending -or actually has a distinct origin from the suffix -er. The ending -tor or -sor was used to form agent nouns in Latin, and words formed with this ending were borrowed into French and English. I wrote a prior answer covering some of the history of this at What’s the rule for adding “-er” vs. “-or” when forming an agent noun from a verb?

The relevance of this distinct origin is that words taken from French sometimes show different accentuation patterns. You might be familiar with how today, French words sound to English speakers like they are accented on the last syllable (unless the word ends in a mute e sound). This seems to have also been true in the past, in Middle English. However, many words that Middle English speakers borrowed from French with stress on the final syllable have come to have anglicized stress patterns where the stress has been 'retracted' to the third-to-last syllable instead. (This seems to be based on a secondary stress that originally fell on alternating syllables before the primary stress.)

Therefore, if we take as our the starting point the Anglo-Norman noun executour (see Etymonline), a Middle English speaker might have pronounced it as something like [egˌze.kiuˈtuːr] eˌxecuˈtour. As the word passed from Middle English to modern English, the stress on the final syllable was lost, and the secondary stress on the third-to-last syllable became the primary stress, giving the modern pronunciation used in a legal context (eˈxecutor).

We also see unexpected (from a Modern English perspective) stress patterns in some adjectives ending in -able, for the same reason: not all of these adjectives were formed in English, but some were borrowed already-formed from French, with stress originally on the -a- of -able. So revocable can be stressed on the first syllable because it corresponds to Old French revocable, which sounded to English-speaking ears like it had stress on the third syllable. We can assume this word originally was pronounced by English speakers with stress on alternating syllables, ˌrevoˈcable, and the primary stress was eventually retracted to the earlier stressed syllable, which originally had secondary stress, giving us ˈrevocable.