My intuition is to capitalize any word that used in reference to a person in place of their name: Mother, Father, Grandma, Grandpa, Doctor, Captain, Professor, Sir, Ma’am, Boss, etc. But my research seems to indicate some of these are proscribed: sir is capitalized only when it's being prepended to the name of a knight, and ma'am is never capitalized.

What’s the rule—or, if guidance differs, what are the rules—here?

I am not asking about cases where one of these words is used with an article such as the. In these cases, the standard seems to be no capitalization: the doctor, the captain, the professor. Nor am I asking about the case where one of these words is prepended to a name as is the chivalric Sir mentioned above. In these cases, capitalization seems standard: Doctor Jones, Captain Smith, Professor Brown.

What I’m wondering is this: what makes the sir in “yes, sir” any different from the Dad in “hi, Dad”? They’re both titles used in place of someone’s name, but one is capitalized and the other isn’t—what rule governs that? And which side of this rule do things like the C/captain in “aye aye, C/captain” fall onto?

Is it that sir is normally only used in vocative address, whereas Dad is also used in third-person reference?

According to Capitalizing Personal Titles as Substitutes for Names, at least some style guides recommend say that formal titles like chancellor and chairman should be capitalized only if they precede a name... but what about Father as used in vocative address to a Catholic priest? If it’s capitalized, it’s an exception because it violates this rule; but if it’s not capitalized, it’s an exception because it’s an (albeit fictive) kinship term, and kinship terms are universally capitalized in the vocative.

  • 'Sir' isn't a title in 'Good morning, sir'. If you would capitalise 'Doctor' in 'Doctor Smith', why not 'Father' in 'Father Brown'? Commented Oct 24, 2021 at 17:13
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    You may well find Sir used as third-person, "I gave it to Sir," although this might not be classed as Standard English.
    – Andrew Leach
    Commented Oct 24, 2021 at 18:36
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    @AndrewLeach Remember "To Sir With Love"?
    – Barmar
    Commented Oct 25, 2021 at 4:05
  • @MichaelHarvey I’m not asking about the “Father” in the phrase “Father Brown”. I'm asking about the case where you’re confessing to him and say, “Forgive me, F/father, for I have sinned.” This is a tricky case because it is both a non-prenominal use of a prenominal title (which many style guides say should not be capitalized) and a kinship term (which is pretty much universally capitalized). Commented Oct 25, 2021 at 18:36
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    @Barmar That's a bit different because it's styled after a letter salutation, and those use special rules (cf. "Dear Sir or Madam"). Commented Oct 25, 2021 at 18:47

1 Answer 1


According to this blog... yes, guidance differs. "Those of you looking for hard and fast rules on this issue are doomed to disappointment." But let's agree, for starters, that it all hinges on direct address. If you side with the up-stylers, you capitalize Padré when addressing the priest because you're addressing him, and would still capitalize it if you wanted to call him "Dude." (At this point, my inner conflict between the stickler and the realist comes to blows over "Hey, You!")

It also notes, "For reasons lost in the mists of time (or at least not immediately findable on the Internet)" words like "sir," "ma'am," or "m'lady" are never capitalized. Trying to track down an explanation does indeed yield an amusing array of confused and clearly false answers. If I had to guess it would simply be that familiarity breeds contempt, and such addresses have been bandied about for so long that we can't take the time to capitalize them (let alone provide all the letters).

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