What is the meaning of tab?

noun

• The bill in a restaurant.
  • usage: "he asked the waiter for the check"
  • synonyms: check, chit
• Sensationalist journalism.
  • synonyms: yellow journalism, tabloid
• The key on a typewriter or a word processor that causes a tabulation.
  • synonyms: tab key
• A short strip of material attached to or projecting from something in order to facilitate opening or identifying or handling it.
  • usage: "pull the tab to open the can"; "files with a red tab will be stored separately"; "the collar has a tab with a button hole"; "the filing cards were organized by cards having indexed tabs"
• A dose of medicine in the form of a small pellet.
  • synonyms: pill, lozenge, tablet