/ˌgastrō(k)ˈnēmēəs/
Noun, pl. gastrocnemii
1. The muscle at the back of the calf, whose insertion is the Achilles tendon at the heel. (wiktionary.org)
2. A very powerful superficial bipennate muscle that is in the back part of the lower leg. It runs from its two heads just above the knee to the heel, and is involved in standing, walking, running and jumping. Along with the soleus muscle it forms the calf muscle. Its function is plantar flexing the foot at the ankle joint and flexing the leg at the knee joint. (wikipedia.org)
3. Origin, by two heads (lateral and medial) from the lateral and medial condyles of the femur; insertion, with soleus by tendo calcaneus into lower half of posterior surface of calcaneus; action, plantar flexion of foot; nerve supply, tibial. (biology-online.org)
4. The chief muscle of the calf of the leg, which flexes the knee and foot. It runs to the Achilles tendon from two heads attached to the femur (Google Dictionary)
Syn: musculus gastrocnemius, gastrocnemius
Word origin: From Latinized form of Greek gastroknemia “calf of the leg,” from gaster “belly” + kneme “leg.” So called for its form.