Define should. should synonyms, should pronunciation, should translation, English dictionary definition of should. aux.v. Past tense of shall 1. Used to express obligation or duty: You should send her a note. 2. Used to express probability or expectation: They should. SHOULD meaning: 1. used to say or ask what is the correct or best thing to do: 2. used to show when something is…. Learn more. SHOULD definition: 1. used to say or ask what is the correct or best thing to do: 2. used to show when something is…. Learn more. Find out how to use the modal verb 'should'. We'll also study the question form and the negative. This article explains the use of should in sentences in English grammar. It also describes the use of should, use of shall, and would and use of ‘should have’. SHOULD definition: must; ought (used to indicate duty, propriety, or expediency). See examples of should used in a sentence. The meaning of SHOULD is —used in auxiliary function to express condition —usually used with if. How to use should in a sentence. The simple definition of SHOULD is —used to say or suggest that something is the proper, reasonable, or best thing to do. should (third-person singular simple present should, no present participle, no simple past or past participle) (modal, auxiliary, defective) Ought to; indicating opinion, advice, or instruction, about what is required or desirable. Used to issue an instruction (traditionally seen as carrying less force of authority than alternatives such as 'shall' or 'must'). We use the English model verb should in a few different situations. We very often use it when we give advice: For example, If you often get headaches, you should go to the doctor. If you want to improve your English, you should take English classes.