funambulist

n. acrobat who performs on a tightrope, tightrope walker

Tightrope walking (or funambulism) is the art of walking along a thin wire or rope usually at a great height. One or more artists perform in front of an audience (a common act in circuses) or as a publicity stunt (often attempting to set location-specific distance or height records). Tightrope walkers sometimes use balancing poles and may perform the feat without a safety net for effect.
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Noun
1. an acrobat who performs on a tightrope or slack rope
(synonym) tightrope walker
(hypernym) acrobat

(n.)
A ropewalker or ropedancer.
  

A tight rope walker