muscle

noun

• 1a band or bundle of fibrous tissue in a human or animal body that has the ability to contract, producing movement in or maintaining the position of parts of the body:the calf muscle [mass noun]:the sheet of muscle between the abdomen and chest
• a muscle or muscles when well developed or prominently visible under the skin:his muscles rippled beneath his tanned skin

Muscles are formed of bands, sheets, or columns of elongated cells (or fibres) containing interlocking parallel arrays of the proteins actin and myosin. Projections on the myosin molecules respond to chemical signals by forming and reforming chemical bonds to the actin, so that the filaments move past each other and interlock more deeply. This converts chemical energy into the mechanical force of contraction, and also generates heat

• 2 [mass noun] physical power; strength:he had muscle but no brains
• informal a man or men exhibiting physical power or strength, typically employed to use or threaten violence:an ex-marine of enormous proportions who’d been brought along as muscle
• power or influence, especially in a commercial or political sphere:many companies lack the financial muscle to adopt a more hard-nosed relationship with buyers

verb

• 1 [with object and adverbial] chiefly North American move (an object) in a particular direction by using one’s physical strength:they were muscling baggage into the hold of the plane
• coerce by violence or by economic or political pressure:he was eventually muscled out of the market