1Used in the pattern ～はずだ to express the speaker's expectation or logical conviction that something should be the case, based on reason or evidence; 'should (be)', 'ought to (be)', 'supposed to be', 'bound to be'. Usually written in kana.
彼女はもう着いているはずだ。
She should have arrived by now.
ちゃんと確認したはずなのに、間違っていた。
I'm sure I checked it properly, yet it was still wrong.
約束したんだから、彼が来ないはずがない。
He promised, so there's no way he won't show up.
この時間なら、お店はまだ開いているはずだ。
At this hour, the shop should still be open.
2The nock of a bow — the part at each end of a bow where the bowstring is fastened. Written with the kanji 筈.
弓の両端の筈に弦を掛ける。
Fasten the bowstring to the nocks at both ends of the bow.
3The nock of an arrow — the notch at the rear end of an arrow that fits onto the bowstring. A term used in Japanese archery.
矢の筈を弦につがえて構える。
Fit the arrow's nock onto the bowstring and take aim.
4In sumo, a hand shaped like a nock, formed by spreading the thumb away from the fingers, used to push against an opponent's armpit or side (as in はず押し / hazu-oshi).
力士は相手の脇に筈を当てて押し上げた。
The wrestler set his nock-shaped grip against his opponent's side and pushed him up.
5A wooden frame fitted to the tip of the mast on a traditional Japanese ship to keep the hawser from slipping off. A nautical term.
帆柱の先の筈に綱を通して固定した。
They ran the hawser through the frame at the masthead and secured it.