The state or feeling of being slightly drunk — that early, pleasant stage after a drink or two when you feel warm, relaxed, talkative, and a little unsteady, but you are still perfectly aware of what you are doing. It is the noun for the condition itself, so it fits in sentences where you talk about the feeling as a thing: it can arrive, wear off, be pleasant, be hidden. It is not a common everyday word; in conversation people usually just say "I'm a bit tipsy" and use the adjective instead. You will meet "tipsiness" mostly in writing — a novel, an article about alcohol, a restaurant review. Like "tipsy", it stays on the gentle, harmless side of drinking; the heavier words are "drunkenness" and, for the medical condition, "alcoholism".