Learn English – What do you call that little area just inside the front door of some houses

Boss In engineering, a boss is a protruding feature on a workpiece. A common use for a boss is to locate one object within a pocket or hole of another object.

See the pictures from this search for examples like yours.

Let me elaborate for you with this update:

Here is a fairly comprehensive book on plastic part design that covers bosses and other plastic part features in great detail. It’s a searchable book, and you might find it helpful for what you are doing.

Boss is the generic name given to the protruding feature in a mechanical design. As you recognize, the function of that protuberance varies, and it can be a protruding pin or a reinforced hole (or a protruding pin with its own hole (See here).

Terms like locating pin or tab and locating hole or slot are common. Pilot holes (in a boss) accept screws or threaded inserts. I haven’t seen any authoritative mention of terms like “male boss” and “female boss”. You can search the above-mentioned book yourself for terms that are used.

Bosses aren’t limited to plastic design, and any fabricated item might have a boss. The boss might be inserted into a second part in an assembly, fastened by whatever means the designer chooses (e.g. screwing, welding).

I'll throw down on this one. Let's say that anyone who is dating is looking for "Mr. Right", or "Ms. Right". But they haven't found them yet. The person they date while waiting may be referred to as "Mr. Right Now" (or "Ms. Right Now").