"Altogether" (one word) = entirely, in total, on the whole; "all together" (two words) = everyone or everything in the same place or at the same time.
Adverb with three uses: (1) entirely/completely ("not altogether sure"); (2) in total, when adding everything up ("that comes to $45 altogether"); (3) on the whole, considering everything ("altogether, it was a good year").
He was not altogether satisfied with the results, but agreed to move forward.
Altogether, the renovation cost nearly three times the original estimate.
She stopped going to the gym altogether after her injury and switched to swimming instead.
Adverb phrase: everyone or everything in the same place or acting simultaneously. "All" intensifies "together". If you can insert other words between "all" and "together" — like "all sitting together" or "all working together" — they are two words.
We were all together in the living room when the power went out during the storm.
The whole family was all together for the first time in three years at the reunion.
Now, class, let us read the paragraph all together — everyone on the count of three.
Common mistake
Test: try moving "all" or inserting a word between "all" and "together". "They were all sitting together" (you can insert "sitting") = two words: "they were all together". If you cannot separate "all" because it forms a single adverb, use one word: "altogether different". Another test: replace with "entirely" or "in total" — if it works, use ALTOGETHER.
Trick to remember it
Replace with "entirely" or "completely": if it works, use ALTOGETHER (one word). "It is altogether wrong" = "It is entirely wrong." Replace with "everyone in one place" or "at the same time": if it works, use ALL TOGETHER (two words). "We were all together" = "We were all in one place." Movable "all" trick: if "all" can be moved or separated, use two words.
Quick rule
Altogether (one word) = entirely / in total / on the whole (replaceable by "entirely" or "in total"). All together (two words) = everyone in the same place or at the same time.
Did you know?
"In the altogether" is a British English idiom meaning "completely naked" (in the buff). "She posed in the altogether for the portrait" = she posed nude. This phrase is several centuries old and curiously uses the one-word form, confirming that "altogether" as a unit has its own idiomatic life beyond its three standard meanings.
Exercise 1 · Pick the right one
The committee voted to abandon the project _____ after the costs exceeded the budget by 200%.
Exercise 2 · Pick the right one
The whole team was _____ in the conference room when the announcement was made.
Exercise 3 · Form the word
Altogether (one word) = entirely / in total / on the whole (replaceable by "entirely" or "in total"). All together (two words) = everyone in the same place or at the same time.
Test: try moving "all" or inserting a word between "all" and "together". "They were all sitting together" (you can insert "sitting") = two words: "they were all together". If you cannot separate "all" because it forms a single adverb, use one word: "altogether different". Another test: replace with "entirely" or "in total" — if it works, use ALTOGETHER.
Replace with "entirely" or "completely": if it works, use ALTOGETHER (one word). "It is altogether wrong" = "It is entirely wrong." Replace with "everyone in one place" or "at the same time": if it works, use ALL TOGETHER (two words). "We were all together" = "We were all in one place." Movable "all" trick: if "all" can be moved or separated, use two words.
Bryan López
Founder of SpeakUP Academy