alive
Living, or full of energy and activity.
Alive means having life, being living rather than dead. A tree is alive because it grows and responds to sunlight and water. A rock isn't alive because it doesn't grow, breathe, or change on its own. When doctors say someone is alive after an accident, they mean the person's heart is beating and they're breathing.
But alive also describes a special quality of energy and awareness. When you feel truly alive, you're fully awake to the world around you: noticing colors more vividly, feeling your body move, engaging completely with what you're doing. A classroom discussion comes alive when everyone participates eagerly. A story comes alive when the details make you feel like you're right there watching it happen.
Something can be kept alive even without being literally living. You might keep your grandmother's memory alive by sharing stories about her. A tradition stays alive when people continue practicing it generation after generation. Scientists might keep cells alive in a laboratory for research.
The opposite of alive is dead for living things, or lifeless and dull for things that lack energy or vitality.