Buy: we do some kind of business with this company, so please keep them liquid.
Sell: we cover this stock and want you to sell so we can buy this stock cheaper.
Hold: we used to cover this stock and liked it, but only you should hold it right now.
Accumulate: we own a lot of this stock and plan to sell some gradually over time.
Reduce: we have a small stock position in this company so don't dump it too fast please.
Neutral or Avoid: we hope to buy this one cheaper, please look for something more interesting.
Agressive Buy or Sell: see above, plus we have a ton of stock (or big short position) already.