whatever
Anything is fine; it does not matter which one.
Whatever is a word that means “anything at all” or “it doesn't matter which.” When your teacher says “bring whatever supplies you need,” she means you can bring any supplies that will help. When someone asks what you want for dinner and you say “whatever,” you're saying any choice is fine with you.
The word also expresses indifference or dismissal. If you suggest playing soccer and your friend responds “whatever” with a shrug, they're showing they don't really care either way. Sometimes people use it more dismissively: when someone doesn't want to keep arguing, they might say “whatever” to mean “I'm done discussing this.”
Whatever can introduce possibilities: “Whatever happens, we'll figure it out” means no matter what occurs, you'll handle it. It can also emphasize unlimited scope: “Take whatever time you need” means there's no restriction on how much time.
The tone matters enormously. Said cheerfully, “whatever works!” sounds helpful and flexible. Said with an eye roll, “whatever” can sound rude and disrespectful. Context and tone can turn this useful word into either a sign of easygoing flexibility or a signal that someone's checking out of the conversation.