1tab 
/ˈtæb/ noun
plural tabs /ˈtæb/ noun [count] 1 a : a small, flat piece on a box, envelope, etc., that can be put into a hole in order to hold two parts together
▪ Insert the tab into this slot to close the box.
b : a small, flat piece that sticks out from the edge of something (such as a folder) and allows you to identify and find it easily
▪ a notebook with index tabs
c US : a small piece of metal, plastic, etc., that is pulled in order to open or close something
▪ The tab on the zipper is broken. ▪ the tab [=(US) pull tab, (Brit) ring pull] on a can of soda 2 US, informal : a record of the things (such as drinks at a bar) that a customer has ordered and will pay for later
▪ He ran up a $200 bar tab. ▪ The final tab [=bill] came to $200. ▪ He put the drinks on his tab. ▪ She offered to pick up the tab. [=pay the bill] for the meal. 3 : tab key
▪ You can move to the next column in a table by pressing tab. [=by pressing the tab key] 4 informal : a small pill of an illegal drug
▪ a tab of Ecstasy
▪ Insert the tab into this slot to close the box.
b : a small, flat piece that sticks out from the edge of something (such as a folder) and allows you to identify and find it easily
▪ a notebook with index tabs
c US : a small piece of metal, plastic, etc., that is pulled in order to open or close something
▪ The tab on the zipper is broken. ▪ the tab [=(US) pull tab, (Brit) ring pull] on a can of soda
▪ He ran up a $200 bar tab. ▪ The final tab [=bill] came to $200. ▪ He put the drinks on his tab. ▪ She offered to pick up the tab. [=pay the bill] for the meal.
▪ You can move to the next column in a table by pressing tab. [=by pressing the tab key]
▪ a tab of Ecstasy
keep tabs on
informal : to carefully watch (someone or something) in order to learn what that person or thing is doing
▪ We are keeping tabs on their movements. ▪ The magazine keeps tabs on the latest fashion trends.
▪ We are keeping tabs on their movements. ▪ The magazine keeps tabs on the latest fashion trends.
