be off
1. To leave a place or to depart to another one. Though formerly used as an imperative, this use is now rare. I'm just off to the bar for a few drinks, I shouldn't be there long. I think I'll be off, talk to you soon.
2. Of food, to be spoiled, rotten, or past its prime. This chicken is definitely off, it stinks!
3. To be slightly unwell or in poor condition. My stomach is off, I think it's from something I ate. I'm not sure what's wrong, I'm just a bit off today.
4. To be incorrect, faulty, or in poor condition. Often used with qualifying words, such as "a bit," "far," "really," etc. It was a nice guess, but you're a little off. That radio is a bit off, it's picking up mostly static. I think we need a different color paint, this one is a little off.
5. Without obligation to or free from something, especially work or school. I'm finally off for my summer vacation! Jonah's off today, he'll be back in the office on Monday.
6. In stocks and finance, to be trading at a value lower than the previous one or lower than the value that was expected or hoped for. The market is off by a huge margin today. This could spell trouble for the economic recovery. The company's stocks are off another 200 points as of this afternoon.
7. To be somewhat strange, crazy, or awkward. Often used with "a bit" or "a little." There's a guy on our corner who shouts about the end of the world; I think he's a little off.
be off
1. Leave, depart, as in I'm off to the races; wish me luck. This phrase, first recorded in 1826, was once commonly used as an imperative, meaning "go away"-as in Be off or I'll call the police-but today is rare in this context.
2. Be in poor condition; be stale or spoiled; not work properly. For example, This milk must be off; it tastes sour, or The kitchen clock is off by at least five minutes. [Early 1990s]
3. Be free from work, school, or some other regular occupation, as in The secretary is off today, but perhaps I can find it. [Mid-1800s]
4. Decline, as in The industrial stocks are off 50 points today. This usage, nearly always applied to securities or other prices, was first recorded in 1929, the year of the great stock market crash.
be off
v.1. To have left or been removed from a surface: The crows have flown away; they're all off the roof now. The snow is off the roads, and it should be safe to drive now.
2. To leave or have left: I was already off to the airport when you called.
3. To be disengaged, not currently functioning, especially through lack of power supply. Used mostly of machines: It's dark now that the lights are off. Before I leave the house I always checks to see if the stove is off.
4. To be no longer connected to or broadcast by some communication system: How long have you been off the phone? The television program is now off the air.
5. To be inexact, imprecise, or not meeting expectations: Something is wrong with this calculation; these figures are definitely off. My golf playing was really off last weekend.
6. To be spoiled: Don't use this milk in your tea; it's off.
7. To be no longer dependent on, addicted to, or desirous of something: I'm finally off caffeine. He's been off of drugs for a long time now.