should

strong /ʃʊd/ weak /ʃəd/ modal verb

Definition

BEST › used to say or ask what is the correct or best thing to do: He should have gone to the doctor. Should I apologize to her? You shouldn't be so angry with him.

EXPECT › used to say that you expect something to be true or that you expect something to happen: She should be feeling better by now. The letter should arrive by Friday.

POSSIBLE formal › used to refer to a possible event in the future: Should you have any further queries, please do not hesitate to contact me. I'll be in my office, if anyone should ask.

why should/shouldn't...? › used to ask or give the reason for something, especially when you are surprised or angry about it: He told me to forgive her, but why should I?

(Definition of should modal verb from the Cambridge Learner's Dictionary © Cambridge University Press)