Yes, STIPULATIONS is a Scrabble word!

Letter values in Scrabble US: S 1, T 1, I 1, P 3, U 1, L 1, A 1, T 1, I 1, O 1, N 1, S 1.

Is it a valid word?

STIPULATIONS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

(law) an agreement or concession made by parties in a judicial proceeding (or by their attorneys) relating to the business before the court; must be in writing unless they are part of the court record
an assumption on which rests the validity or effect of something else
a restriction that is insisted upon as a condition for an agreement

Also: judicial admission.