Uneducated means not having had much schooling — or showing the signs of that. It works two ways. About a person: 'she was poor and uneducated' simply states that she did not get to go to school for long. About speech, writing, or manners: 'an uneducated accent', 'uneducated handwriting' — here the word is judging how someone comes across, and that use is often unkind. Handle it carefully. Uneducated is not a neutral technical word in the way it looks; in English it carries a strong social smell, and calling a living person uneducated to their face, or in an essay, sounds looking-down-your-nose. Native speakers usually soften it: 'he left school early', 'she never had the chance to study'. It is safest in historical or statistical writing — 'a largely uneducated population in the nineteenth century'. Keep it apart from three near neighbours. Uneducated is about schooling. Ignorant is about not knowing a particular thing (and is ruder). Illiterate specifically means unable to read and write. Stupid is about ability, and is different again — a highly intelligent person can be uneducated, and that gap is exactly the point the word often makes. In older writing you will also meet 'the uneducated' as a group noun, meaning uneducated people generally.