The formation of bones.
i have no clue
There is no English word that contains those exact letters. However, you can make a few 7-letter words if you repeat some of the letters: isotopy, ostosis, piosity, soffits, stypsis, tipoffs, tiptops, tosspot, typists.
ascarid, ascaris, ascesis, ascetic, ascidia, ascitic, asepsis, aseptic, askesis, aspirin, astasia, astatic, asteria, isogriv, isospin, isthmic, osmatic, osmosis, osmotic, ossific, osteoid, ostosis, psalmic, psoatic, psychic, psyllid, tsaddik, tsooris, tsouris
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 1 words with the pattern -STO-I-. That is, seven letter words with 2nd letter S and 3rd letter T and 4th letter O and 6th letter I. In alphabetical order, they are: ostosis
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 9 words with the pattern --T-SI-. That is, seven letter words with 3rd letter T and 5th letter S and 6th letter I. In alphabetical order, they are: astasia cutesie ectasia ectasis entasia entasis ketosis mitosis ostosis
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 2 words with the pattern -STOS--. That is, seven letter words with 2nd letter S and 3rd letter T and 4th letter O and 5th letter S. In alphabetical order, they are: ostoses ostosis
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 9 words with the pattern -ST--I-. That is, seven letter words with 2nd letter S and 3rd letter T and 6th letter I. In alphabetical order, they are: astasia astatic astelic asteria asterid astroid isthmic osteoid ostosis
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 1 words with the pattern O-T-SI-. That is, seven letter words with 1st letter O and 3rd letter T and 5th letter S and 6th letter I. In alphabetical order, they are: ostosis
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 2 words with the pattern -S-OSI-. That is, seven letter words with 2nd letter S and 4th letter O and 5th letter S and 6th letter I. In alphabetical order, they are: osmosis ostosis
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 2 words with the pattern O-TOS--. That is, seven letter words with 1st letter O and 3rd letter T and 4th letter O and 5th letter S. In alphabetical order, they are: ostoses ostosis
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 6 words with the pattern -S--SIS. That is, seven letter words with 2nd letter S and 5th letter S and 6th letter I and 7th letter S. In alphabetical order, they are: ascesis asepsis askesis osmosis ostosis tsotsis
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 4 words with the pattern -S-OS-S. That is, seven letter words with 2nd letter S and 4th letter O and 5th letter S and 7th letter S. In alphabetical order, they are: osmoses osmosis ostoses ostosis