-sə(r) noun
( -s )
Etymology: Late Latin, from Latin depressus + -or
: something that depresses: as
a. : a muscle that depresses or draws down a part — compare levator
b. : a device or appliance that depresses a part
a tongue depressor
c. : a nerve or nerve fiber that decreases the activity or the tone of an organ
d. : depressant
e. : a substance (as a drug) that lowers blood pressure
f. : a substance that retards or prevents a chemical reaction or process