noun

• (music) A company that sells records.
  "The label signed the band after hearing a demo tape."
• (computing) A user-defined alias for a numerical designation, the reverse of an enumeration.
  "Storage devices can be given by label or ID."
• (computing) A named place in source code that can be jumped to using a GOTO or equivalent construct.
• (heraldry) A charge resembling the strap crossing the horse’s chest from which pendants are hung.

verb

• (transitive) To put a label (a ticket or sign) on (something).
  "The shop assistant labeled all the products in the shop."
• (ditransitive) To give a label to (someone or something) in order to categorise that person or thing.
  "He's been unfairly labeled as a cheat, although he's only ever cheated once."
• (biochemistry) To replace specific atoms by their isotope in order to track the presence or movement of this isotope through a reaction, metabolic pathway or cell.
• (biochemistry) To add a detectable substance, either transiently or permanently, to a biological substance in order to track the presence of the label-substance combination either in situ or in vitro
  "They may be used to label and image a protein within tissue, to isolate cells on the basis of marker expression, or to physically capture a protein from a complex biological mixture...."