| intrepid(adjective, energetic, daring, resourceful, innovative) |
| involved(adjective, bright, energetic, active, vigorous) |
| irrepressible |
| itching(adjective, energetic, daring, resourceful, innovative) |
| jocund(adjective, bright, happy, energetic, active) |
| jolly(adjective, happy, merry, cheerful, joyful) |
| jovial(adjective, happy, merry, cheerful, joyful) |
| joyful(adjective, happy, merry, cheerful, cheery) |
| joyous(adjective, happy, merry, cheerful, joyful) |
| jubilant(adjective, happy, merry, cheerful, joyful) |
| juiced up(expression, adjective, happy, merry, cheerful) |
| jumping(adjective, strong, happy, firm, energetic) |
| kinetic |
| know-how(adjective, alert, familiar, wise, knowledgeable) |
| know the score(expression, adjective, idiom, alert, familiar) |
| knowing(adjective, alert, familiar, wise, knowledgeable) |
| knowledgeable(adjective, alert, familiar, wise, responsive) |
| latched on(expression, adjective, alert, familiar, wise) |
| latest(adjective, smart, hot, elegant, current) |
| lax |