Select the CORRECTLY spelt word.

To find the correctly spelt word, let us analyze the spelling of each option one by one:

1. embarass: This spelling is incorrect. The correct spelling is embarrass, which has a double 'r' and a double 's' (e-m-b-a-r-r-a-s-s).
2. enviroment: This spelling is incorrect. The correct spelling is environment, which must include the letter 'n' before the suffix '-ment' (e-n-v-i-r-o-n-m-e-n-t).
3. cigarette: This spelling is correct. It is spelled with a single 'r' and a double 't' followed by 'e' (c-i-g-a-r-e-t-t-e).
4. seperete: This spelling is incorrect. The correct spelling is separate (s-e-p-a-r-a-t-e).

Therefore, the correctly spelt word is cigarette.