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
nounpl. triceps triceps
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)