어

Casual sentence ending, no politeness

Ends a sentence with no politeness attached — the footing used with close friends, with people younger than you, within a family, or when muttering to yourself. Every example here is that: "hold on", "we have to get out of here", "I don't know if this will work", "my jaw dropped". Adding 요 to it turns the same sentence into the polite 어요, which is why speakers slide between the two within one conversation depending on who they are addressing.

Register: casual speech between close people