What does ハーレム Harem mean?

Harem (ハーレム) names a household's secluded women's quarters; Japanese fiction turned it into a genre label, now used in English in that sense too.

Written
ハーレム (hāremu)
Literally
A loan the Daijisen dictionary traces to Arabic, used in Japanese as a structural label for a story shape.
As slang
Genre vocabulary rather than everyday speech. In Japanese it describes a configuration of characters, not a household.
In anime
One protagonist surrounded by several potential partners, with the structure itself as the premise rather than as a subplot.

Harem, as a genre term, describes a story built around one character surrounded by several who are romantically interested in them. The word has traveled further than most on this site and has changed jobs at every stop.

Three journeys

The word entered English from Arabic by way of Turkish, referring to the secluded women's quarters of a household. Japanese has the word too, and the genre that originated in Japan in the 1970s took it as a label for a narrative configuration, which is not what it means in English.

English-speaking fandom then took it up in the new sense, so English now contains both meanings: a historical term about domestic architecture and a genre term about a cast arrangement, connected only by a metaphor somebody made in Japanese.

What the genre label actually specifies

A structure, not a content rating. The defining feature is that the configuration is the premise: the story exists to arrange one character among several, and the tension is the arrangement rather than any particular pairing.

This is why the label predicts so little about tone. It covers comedies, dramas, and stories that use the structure to examine why the protagonist cannot choose, and nothing in the word says which.

The inversion has its own name

A version with the sexes reversed is labeled by adding reverse, which is a revealing piece of vocabulary: the unmarked case is a male protagonist, and the other requires a modifier.

That asymmetry is in the English fandom term as much as in the Japanese, and both inherited it from the same assumption about who a story's default audience is.

Why the metaphor is worth questioning

The original referent involves confinement and ownership, and the genre it now names is usually a comedy about an indecisive teenager. The metaphor imports a claim about possession that most of these stories do not support and some actively refuse.

Genre labels are rarely chosen carefully, and this one is a good example of a name that has stuck despite describing the material badly. The structure it points at is real; the word for it is borrowed luggage.

Quick answers

What does harem mean?

A loan the Daijisen dictionary traces to Arabic, used in Japanese as a structural label for a story shape.

Is harem an insult?

Genre vocabulary rather than everyday speech. In Japanese it describes a configuration of characters, not a household.

What does harem mean in anime?

One protagonist surrounded by several potential partners, with the structure itself as the premise rather than as a subplot.