In UK English, is the word HOLIDAY used in legal documents (like an employment contract) where we North Americans would use "vacation"?

yes, it is, look.

https://www.gov.uk/holiday-entitlement-rights/enti...

Your sentence should read "In the UK, is the word HOLIDAY used in legal documents (like an employment contract) where we North Americans would use the American English word "vacation"?

There is no such thing as UK English - there is the English language which we use, and then there is the American version of it.

Yes. The word "vacation" is not used in the UK, except occasionally in referring to university vacations. Employment contracts refer to "holiday" or "leave".

Holiday is the accepted word in the UK - even in legal documents such as employment contracts

In America a holiday is means a general holiday such as Thanksgiving but in the UK it is normal to refer to vacation as holiday as in I m going on holiday for two weeks. So you might get 25 days holiday (meaning vacation), a huge amount compared with most US companies, and 8 public or bank holidays usually New Years Day, Good Friday, Easter Monday, May Day Holiday, Spring Holiday, August Bank Holiday, Christmas Day and Boxing Day (26th Dec)

Yes either holiday or annual leave the word vacation is not used in the UK.

The term UK or British English is never used we speak English

Yes, "holiday" in the UK is the same as American "vacation."

My ecologist contract talks about a"holiday entitlement " of 28'days plus back holidays

Yes it is. We "go on holiday", not "on vacation".

In the UK the term "vacation" is rarely used unless we are talking to foreigners who have only learnt the US language.

In addition to our annual holidays (anything from a week to a month away from work) which we take for rest and recreation, we have 9 Bank Holidays (public and religious holidays) throughout the year. This is why you should NEVER refer to the Christmas period as just "the holidays" when talking to someone from the UK, it will confuse them; the term "holiday" is not that specific - we would always say "the Christmas holiday".

BTW. we invented the language so we would never call it "UK English" or (worse) "British English". Just "English" is sufficient, leave the prefixes (US, Aus, etc) to the foreign dialects.

there is only one English that i spoken in England all the rest are similar but unlike the USA who has Not spoken English or spelt in English since Washington

Our law requires us to have 4 weeks Paid leave for Full time employment within the British Isles

Generally the term used is "leave" so holiday leave or annual leave