1. sth that is absolutely necessary or required
it's imperative to do sth
The word 'imperative' can be used as an adjective or a noun. As an adjective, something 'imperative' is important, crucial or vital: "It was imperative that she took her medication at the same time each day."Similar in meaning to 'crucial' or 'intrinsic'. As a noun, it means an essential or urgent thing: "An imperative for us is our children's education." This word can be used in social and professional contexts, but it is more likely to be used in formal contexts.