[1] : The Collaborative International Dictionary of English v.0.48

sarcolemma \sar`colem"ma\, n. nl., from gr. sa`rx, sa`rkos,
   flesh + ? rind, skin. anat.
   the very thin transparent and apparently homogeneous sheath
   which incloses a striated muscular fiber; the myolemma.
   1913 webster

[2] : WordNet (r) 2.0

sarcolemma
     n : an extensible membrane enclosing the contractile substance
         of a muscle fiber

Sarcolemma >> S Words
Sarcolemma, definition of term: Sarcolemma
sarcolemma_pag1.html