The word ‘hack’ in the context of horses refers to a horse that is for hire or is used for simple riding work. It describes a standard course of moderate quality unsuited to hunting or other specialised purposes or activities.

The word originates from the French word haquenée, which meant a horse that only ambles along and was normally used by ladies. A hack was normally used to pull coaches and was not infrequently over-worked and over-used. This led to the development of the phrase “hackneyed” to mean something which is overused such as the hackneyed use of language.
It also led to the phrase “a hack writer” meaning a writer of average ability. The word is an interesting example of how language evolves.
The current French to English translation of the word haquenée is ‘ambler, ambling horse’.
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