What does "headcount" mean?

The act of counting how many people are present in a group.

Headcount

Common synonyms include: attendance, attendance count, attendance tally, attendances, audience presence, audience size.

/ˈhɛdˌkaʊnt/ noun

noun ·Uncommon ·Advanced level

Noun

1
The act of counting how many people are present in a group.
"Let's take a quick headcount, to make sure we're all here."
2
number of people in a particular group wordnet
3
The number of people present in a group or employed by a company.
"The company's headcount on January 1 was 15,203."
4
More generally, a consideration of a company's appropriate staffing level based on some larger context. (Generally used adjectivally.)
"Due to economic difficulties, the company will be making headcount adjustments."
5
By extension, one slot in a workgroup, filled or to be filled by one person.
"I've convinced management to give us one more headcount, to take some work off the rest of us."

"Let's take a quick headcount, to make sure we're all here."

From head + count.