Learn English – Single-word term for “Number of employees”

If you want a word that matches up with capacity, you can use occupancy for this. Per the OED:

1. a. The condition of being an occupant; the fact of occupying; the act of taking, or fact of holding, actual possession, esp. of land (spec. in Law, the taking possession of something not belonging to any one, as constituting a title to it); actual holding of or residence in a place; = ^{_OCCUPATION1, 2}.

[...]

3. a. The state of being occupied or busy; = ^{_OCCUPATION 4}.

   b. Teleph. The proportion of the time during which a circuit or device is handling calls.

   c. The proportion of accommodation occupied or used.

Basic search gives :

• second result :

It goes by many names: love line, moneymaker, Marky's mark, the Michelangelo muscle.

• third result is a wikipedia article about Groin where you can find an explanation that leads to pectineus muscle article where there is a good schema about the zone. According to the schema, what you are looking for may be called Iliacus muscle.

• fourth result :

It goes by many names (Love-Line, Marky's Mark, Adonis Muscle...)