They are the same word: <em>though</em> is the standard spelling, and <em>tho</em> is an informal respelling used in casual writing. <em>It was cold, though the sun was out</em> is what you write in an essay; <em>cold out, was sunny tho</em> is what you send a friend. No dictionary treats <em>tho</em> as suitable for formal prose.
The core difference
Nothing separates them in meaning, grammar or pronunciation. Tho is a simplified spelling that drops the silent -ugh, and it functions exactly like though in every position — as a conjunction, as a trailing adverb, and in the fixed phrases.
The difference is entirely social. Though is neutral and passes anywhere. Tho signals casualness, and in the wrong document it reads as carelessness rather than style.
How to use though
- Conjunction (introducing a concession): Though the flat was tiny, it had a balcony.
- Trailing adverb (meaning however): It rained all week. We went anyway, though. This use is very common and completely standard, including at the end of a sentence.
- Fixed phrases: as though (She spoke as though nothing had happened), even though (Even though he apologised, nobody moved).
The test
Would an emoji fit in the same sentence? If yes, tho is fine. If the sentence is going into a report, an application, an article or anything with a named author, write though. There is no cost to using the full spelling in casual writing, so though is always the safe default.
Though or although?
The more useful distinction for most writing is between though and although. They are interchangeable as conjunctions, with two exceptions:
- Only though can trail at the end of a clause meaning however: It's expensive, though. Never "It's expensive, although."
- Although is a touch more formal and is preferred at the start of a long sentence in careful prose.
The common mistake
Watch for tho colliding with through, which some people also shorten to thru. The two are unrelated words with unrelated meanings — one concedes a point, the other means passing from one side to the other — and mixing the informal spellings in the same message makes both harder to read.
The other slip is punctuation. When though trails at the end, it takes a comma before it: I'd rather not, though. When it opens a clause, put the comma after that clause, not after though: Though I agreed, I said nothing.
Frequently Asked Questions
Can I use "tho" in an email at work?
Better not. Even in a relaxed office it reads as text-message spelling, and it costs nothing to type the two extra letters. Keep it for messages to friends.
Is it wrong to end a sentence with "though"?
No, that is entirely standard. "It's a long drive, though" is ordinary English and means the same as starting the sentence with however.
What's the difference between "though" and "although"?
They mean the same as conjunctions, and although is slightly more formal. Only though can be used on its own at the end of a clause to mean however.