officious
Bossy and pushy about giving unwanted help or advice.
Officious means overly eager to offer unwanted help, advice, or interference, especially in a bossy or self-important way. An officious person inserts themselves into situations where they haven't been asked and aren't really needed, acting like they're in charge when they're not.
Imagine a classmate who constantly tells other students how to do their work, interrupts to “correct” people, and acts like an unofficial teacher's assistant even though nobody asked for help. That's being officious. Or picture someone at a family gathering who bosses everyone around about how to set the table, what food to serve, and when to eat, even though they're just a guest.
The word carries a distinctly negative feeling. It's not about being genuinely helpful. It's about being pushy, meddlesome, and annoying. An officious hall monitor might lecture students for the tiniest infractions and act more important than actual teachers. An officious neighbor might constantly tell you how to mow your lawn or trim your hedges.
Officious is easy to confuse with official (authorized or formal), but they're quite different. An official referee has real authority. An officious bystander just acts like they do.