One of our readers, D Lynch, asked me to provide definitions to some terms I throw around on the blog from time to time. That makes good sense.
So here are a few phrases you might read from time to time:
Throw a bullpen: This is essentially a practice session for pitchers. They will literally go to the bullpen and throw 30 or so pitches. Starters throw a bullpen in between starts, usually two days before they pitch. Some guys throw their regular pen then a “light pen” the day after. This is also known as a side session.
Dry swings: Hitters come back from injuries often take a bat and swing at nothing, just to get their muscles used to the motion. You’ll often hear that somebody rehabbing an injury “took dry swings for 10 minutes.”
Long toss: This is just what it sounds like. Players will throw the baseball back and forth starting from 50 feet away and branching out to 200 feet. It’s how they build up arm strength. A pitcher coming back from injury will often “throw long toss” before he gets on the mound.
Soft toss: This is what hitters do. They will stand in the cage with a bat and swing at balls tossed in front of them by a coach. An injured hitter will “take some soft toss” before he takes full BP.
BP: That stands for batting practice. You get in the cage, a coach throws some nice down-the-middle pitches and you swing at them.
Simulated game: Just like it sounds. A pitcher will get on the mound and face two or three hitters. Each guy stands at the plate until he makes an out or gets on base. Just a way for a pitcher to get some work in.
The line for a pitcher: That’s shorthand for the box score line. Let’s say I wrote: “Joba’s line was 7 2 1 1 2 7.” That means Joba went seven innings, allowed two hits, one run, one earned run, two walks and had seven strikeouts.
Optioned: When a player on the 40-man roster is sent to the minor, he is “optioned out” or “optioned down.” Players generally have three options, although in some cases they can have four depending on time on the disabled list. One option lasts the course of the season.
Other transactions: This Wikipedia entry  explains some other terms.
If I’m missing something, just ask. I’ll be happy to add to this list.