We don't have synonyms for thair yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are hair, chair and Thai.
(adv) :
Archaic spelling of there. [(location) In or at a place or location (stated, implied or otherwise indicated) that is perceived to be away from, or at a relative distance from, the speaker (compare here).]
(adv) :
Archaic spelling of there. [(location) In or at a place or location (stated, implied or otherwise indicated) that is perceived to be away from, or at a relative distance from, the speaker (compare here).]