In many objects in daily life, for example a remote control battery cover, there's usually a protrusion that slides into a socket to retain the object.

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What do you call this protrusion?

A word used in mechanical engineering would be best.

  • 2
    'Battery cover', as you yourself do. I doubt there's a single-word synonym. // Some boxes have sliding lids. Apr 29, 2023 at 18:08
  • 3
    tongue and groove Apr 29, 2023 at 20:15
  • 3
    The actual protrusion that fits into a slot would probably be called a tab or a hook or even a hooked tab, and the tab/slot mechanism combined could be considered a latch.
    – Hellion
    Apr 29, 2023 at 21:08
  • 1
    Sometimes called a "hatch", but I don't see it as a protrusion. A protrusion is something that sticks out (protrudes) permanently, not something which protrudes only when it's moved out of the way. A protrusion which fits into an aperture is a tenon but that protrudes permanently from the component of which it is a part and is hidden only because it is fitted into the mortice which is a hole cut into another component.
    – BoldBen
    May 1, 2023 at 7:29
  • 1
    If you want a precise engineering term, rather than an informal term a non-engineer would use, ask in engineering.stackexchange.com not here.
    – Stuart F
    May 1, 2023 at 12:30

3 Answers 3


Unless there's some unusual term specific to the engineering profession, I think "tongue and groove" fits the bill better than anything else I can think of. The bit that sticks out is the tongue, and the slit it fits into is the groove.

I don't think it would apply to a similar structure where there's a ridge along which another part slides (as you might have along the sides of a cover such as pictured in OP.) Tongue and Groove is specific to a particular point on the structure.

Less colorfully, you may simply call it a "tab" and "slot"


I don't believe there is a single name for these. Names which can be used include

  • The term specific for the case you showed is battery compartment slide(r), but there are other more generic terms for other variants implied in your question.

  • accessible compartment cover

  • battery access slider

  • battery flap

  • compartment door


If the question is about a small part that flexes to snap into a cutout or recess, thereby locking the cover in place -- not just asking about the cover, then here's an answer:

Besides holding a cover in place, similar parts are on an Ethernet RJ plug and Display Port connector. There's a tiny notch that snaps automatically when you plug in the cable. It is released by pressing down on a tiny lever or button to remove the cable.

I do not have one definitive name. These are possibilities used in various contexts: Catch Latch or latching mechanism Tab Finger Hook or hooking tab, latch, finger, etc.

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