What does "tranquilliser" mean?

Non-Oxford British English standard spelling of tranquilizer.

Tranquilliser

Common synonyms include: antianxiety agent, ataractic, ataractic agent, ataractic drug, tranquilizer, tranquillizer.

noun

noun ·Rare ·Advanced level

Noun

1
Non-Oxford British English standard spelling of tranquilizer. UK, alt-of, nonstandard
2
a drug used to reduce stress or tension without reducing mental clarity wordnet

"The tiger was hit by a tranquilliser dart."