Definition of rude adjective from the Oxford Advanced Learner's Dictionary

Oxford3000

rude

adjective
ruːd
 
; ruːd
 
ruder, rudest
 
1 having or showing a lack of respect for other people and their feelings
Synonym
impolite
a rude commentrude (to somebody) (about somebody/something) The man was downright rude to us.Why are you so rude to your mother?She was very rude about my driving.rude (to do something) It's rude to speak when you're eating.How rude of me not to offer you something to drink!There's no need to be rude!I don't wish to be rude, but I have another appointment in five minutes.
2 (especially British English) (North American English usually crude) connected with sex or the body in a way that people find offensive or embarrassinga rude gestureSomeone made a rude noise.The joke is too rude to repeat.3 [only before noun] (formal) sudden, unpleasant and unexpectedThose expecting good news will get a rude shock.If the players think they can win this match easily, they are in for a rude awakening.4 (literary) made in a simple, basic way
Synonym
primitive
rude shacks
rudeness
ruːdnəs
 
; ruːdnəs
 
noun [uncountable]She was critical to the point of rudeness.I want to apologize for my rudeness the other day.
Idioms

in rude health

(old-fashioned, British English) looking or feeling very healthy
Usage noteUsage note: rudecheeky insolent disrespectful impolite impertinent discourteousThese are all words for people showing a lack of respect for other people.rude having or showing a lack of respect for other people and their feelings:Why are you so rude to your mother? It's rude to speak when you're eating.cheeky (British English, informal) (especially of children) rude in an amusing or an annoying way:You cheeky monkey! a cheeky grininsolent (rather formal) very rude, especially to somebody who is older or more important Insolent is used especially to talk about the behaviour of children towards adults.disrespectful (rather formal) showing a lack of respect for somebody/something:Some people said he had been disrespectful to the President in his last speech.impolite (rather formal) not behaving in a pleasant way that follows the rules of society:Some people think it is impolite to ask someone's age. Impolite is often used in the phrases It seemed impolite and It would be impolite.impertinent (rather formal) not showing respect for somebody who is older or more important Impertinent is often used by people such as parents and teachers when they are telling children that they are angry with them for being rude:Don't be impertinent!discourteous (formal) having bad manners and not showing respect:He didn't wish to appear discourteous.rude/cheeky/disrespectful/impolite/discourteous to somebodyrude/impolite/impertinent to do something