Masculine first-person plural pronoun, used among male friends or in rough/casual speech. Not used in polite or formal contexts.
We're going to the beach tomorrow.
Let's do it just by ourselves.
Alternate spelling using the kanji 達 for the plural suffix; less common than 俺たち.
Compound of the masculine first-person pronoun 俺 (ore) and the pluralizing suffix たち (tachi).