0Unimportant is basically the opposite of important. There is no difference in meaning between unimportant and not important, but generally, we would use not important.0-
0 I'd say that IMO in adjectival position, before the nouns, 01b00unimportant 02b00is preferred, esp with several adjectives. 02br 02br 00 However, in predicative position (after verbs) both seem to be used, IMO, with some preference for 01b00not important02b00. 02br 02br 00 See examples at the BBC:02br
0Yes the context makes a difference, as Marius say.02br 02br 00He is an unimportant man. ok.02br 02br 00He is a not important man. not ok.02br 02br 00You forgot to buy the rice? Oh never mind, it's not important. ok.02br 02br 00Your forgot to buy the rice? Oh never mind, it's unimportant. not ok.0-