tranquilize

US: /ˈtræŋkwəˌlaɪz/ ,(trang′kwə līz′)

Inflections of 'tranquilize' (v): (⇒ conjugate)

tranquilizes

v 3rd person singular (US & UK)

tranquilizing

v pres p (US & UK)

tranquilized

v past (US & UK)

tranquilized

v past p (US & UK)

WordReference Random House Learner's Dictionary of American English © 2025

tran•quil•ize or tran•quil•lize /ˈtræŋkwəˌlaɪz/   v. [~ + object] , -ized or -lized, -iz•ing or -liz•ing. 

1. to make tranquil, as by giving a drug to:
   The veterinarian tranquilized the dog with an injection.

WordReference Random House Unabridged Dictionary of American English © 2025

tran•quil•ize  (trang′kwə līz′), v.t., v.i., -ized, -iz•ing. 

1. to make or become tranquil.

Also, tran′quil•lize′;
[esp. Brit.,] tran′quil•lise′.

• tranquil + -ize 1615–25

tran′quil•i•za ′tion, n. 

Collins Concise English Dictionary © HarperCollins Publishers::

tranquillize, tranquillise, tranquilize / ˈtræŋkwɪˌlaɪz/ verb

1. to make or become calm or calmer

ˌtranquilliˈzation, ˌtranquilliˈsation, ˌtranquiliˈzation noun