Definitions
1.nounA small flap or strip of material attached to something, for holding, manipulation, identification, opening etc.
2.nounAn ear.
3.noun(by extension) A navigational widget, resembling a physical tab, for switching between documents or sets of controls.
4.nounThe page or form associated with such a navigational widget."How many tabs are open in your Web browser?"
5.noun(British army) A fast march or run with full kit.
6.verbTo affix with tabs; to label.