The triceps is the muscle that runs along the back of the upper arm.
An example of a triceps is the muscle used to extend your forearm.
a muscle having three heads, or points of origin, esp. the large muscle at the back of the upper arm that extends the forearm when contracted
Origin of tricepsModern Latin from L, triple-headed from tri-, tri- + caput, a head
A large three-headed muscle running along the back of the upper arm and serving to extend the forearm.
Origin of tricepsFrom Latin three-headed tri- tri- caput head ; see kaput- in Indo-European roots.
(plural triceps or tricepses)