of or pertaining to Siam, its people, or their language.

Thai ( def. 3 ) .

twin; closely connected; similar.

Informal . dual; combined; twofold or two-way

a Siamese sprinkler.

a native of Siam.

Thai ( def. 2 ) .

Siamese cat.

( usually lowercase ) a standpipe placed outside a building close to ground level, having two or more openings so that fire engines can pump water to the sprinkler system of the building.