coact, octad, coati, octal, octan, cotan, canto, coapt, taroc, actor, ascot, coats, coast, costa, tacos, cotta.
Your query has returned 11 words, which include anagrams of octa as well as other shorter words that can be made using the letters included in octa.
The words in this list can be used in games such as Scrabble, Words with Friends, Wordscapes and other similar games.