You don't. The letter O is a letter, not a word. The word "oh" is a word but it does not stand for the letter O.
The letters "r r r e o t" can be rearranged to spell the word "trore." However, if we consider the letters more carefully, the correct 5-letter word they can form is "retro."
5 letter word is "Front".
Those letters will spell the seven letter word boombox.
Coralic can be anagrammed to spell "caloric".
The letters spell the words nope, open and peon.
Aconite.
ANSWERRam, mom, rot, mat, rat, oat, roam, at, am, mot, toANSWERYou can form a word from the letter, ammtor. The word is marmot, spelled as m-a-r-m-o-t.
They spell the 5 letter words comer and crook. They also spell the word joker.
The letters can be used to spell the 11 letter word undercounts. They spell the 10 letter word undercoats and the 9 letter words consorted, construed, courteous, outscored, outsoared, tornadoes, transcend, uncounted, undercoat and undercuts.
Original
The six-letter word you can form with the letters O, S, A, C, I, and F is "fiasco."