We don't have synonyms for startler yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are startle, startled and starter.
(n) :
a sudden motion or shock caused by an unexpected alarm, surprise, or apprehension of danger
(v) :
to move suddenly, or be excited, on feeling alarm; to start; to excite by sudden alarm, surprise, or apprehension; to frighten suddenly and not seriously; to alarm; to surprise
(n) :
a sudden motion or shock caused by an unexpected alarm, surprise, or apprehension of danger
(v) :
to move suddenly, or be excited, on feeling alarm; to start; to excite by sudden alarm, surprise, or apprehension; to frighten suddenly and not seriously; to alarm; to surprise