the word tranquilize is a modern english formation, built upon the adjective 'tranquil', which entered english in the early 17th century from latin 'tranquillus'. this latin term, suggesting stillness and serenity, is of uncertain deeper origin but may be related to 'trans-' (across) and 'quies' (rest), implying a state of thorough rest. the productive verb-forming suffix '-ize', with its ancient greek lineage, was appended to 'tranquil' to create a verb meaning 'to make tranquil'. its specialized medical use, referring to inducing calmness or sedation via pharmaceutical means, developed in the mid-20th century with the advent of psychotropic drugs known as tranquilizers.

Structure: tranquil (calm) + ize (verb suffix) tranquil (from latin 'tranquillus', meaning calm, quiet, still; functions as the adjectival root conveying the state to be induced). ize (from greek '-izein' via latin '-izare' and old french '-iser'; a verb-forming suffix meaning 'to make, to render, to become').