We don't have synonyms for boyang yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are loyang, poyang and bonang.
(n) :
Alternative form of bowyang. [(Australia, New Zealand) A strap worn below the knee, especially by labourers, to keep the trousers up or to stop them stretching while bending.]
(n) :
Alternative form of bowyang. [(Australia, New Zealand) A strap worn below the knee, especially by labourers, to keep the trousers up or to stop them stretching while bending.]