tranquillise

verbs

make calm or still
"quiet the dragons of worry and fear"
calm, calm down, lull, quiet, quieten, still, tranquilize, tranquillise, tranquillize
cause to be calm or quiet as by administering a sedative to
"The patient must be sedated before the operation"
calm, sedate, tranquilize, tranquillise, tranquillize
is derived from
tranquilliser