We don't have synonyms for sixteens yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are sixteen, sixteenth and sixties.
(n) :
(sports, snowboarding, skiing) Clipping of 1620 (“1620° spin”). [An aerial maneuver in which the performer spins through four-and-a-half revolutions.]
(n) :
(sports, snowboarding, skiing) Clipping of 1620 (“1620° spin”). [An aerial maneuver in which the performer spins through four-and-a-half revolutions.]