Definition from Wiktionary, the free dictionary
declension of तुम
- तुम is the mid level formal way of expressing "you" in Hindi and is used when addressing those of equal social status or those one has a close enough relationship with to justify the reduced formality. Because the less formal forms could offend others, आप is the safest way to express "you" unless there is reason to be less formal.
- Because तुम is grammatically plural (adjectives and verbs etc affected by it take their plural forms) even when there is only one person being referred to, the term तुम लोग (literally: you people) can be used to specify that more than one person is being referred to.