Visitors, visitor's, visitor or visitors'

[seeker]

Book?

visitors'

But convention will allow a plain 'visitors' too.

Agree with BoF, unless you only ever expect to have the one visitor.

ConventionBeDamned - visitors'.

visitors is fine as it becomes an adjective

However visitors' is surely correct.

But doesn't visitors' book mean the book that belongs to the visitors? And isn't avisitor's book the book belonging to a visitor?

I'm uncharacteristically baffled by this - what am I missing?

But doesn't visitors' book mean the book that belongs to the visitors? And isn't avisitor's book the book belonging to a visitor?

I'm uncharacteristically baffled by this - what am I missing?

The visitors book has a lot of visitors in it. Plural - hence, 'Visitors' Book.

Visiters!! (only joking

As others have said, Visitors Book is fine.

It depends if you are seeing the word as description of the book (an adjective requiring no possessive apostrophe) or a noun designating the book as belonging to/pertaining to the visitors.

A possessive S doesn't necessarily mean possession in the literal sense of belonging to. It can just mean related to. For example if you say "Friday's lunch" - the lunch doesn't belong to Friday. It doesn't belong to anyone. But it is associated with Friday.

in this case, the book relates to lots of visitors, hence visitors' being more correct.

If the book pertained only to one visitor, ie it was the personal possession of one single visitor, one they had left at your house maybe, then "Visitor's book"

Would you like to write in our visitors' book?
Would you like to write in our visitors book?
Both ok.

But:
Could you remember to return the visitor's book when you see him?
Only this is correct.

wot Youngvisiter said seeker.

The book is connected to the visitors - it doesn't need to belong to them.

Like "an hour's drive" - the hour doesn't own the drive, but you would never say "an hour drive" would you?