This is how I refer to things.
DROP SETS (RUNNING THE RACK)
Start with heaviest weight you can that only allows you to do 3-6 reps. Do those reps. Drop down in weight (anywhere from 5 to 20lbs depending). Hit at least 1 more rep than you did the first set. Continue until failure or you run out of weights.
DROP REPS (DESCENDING LADDER)
Pick a weight around 70-80% of your max. Do as many reps as possible. When you come back do 1-2 less reps than last set. Continue for certain number of sets or failure.
ASCENDING LADDER
Do 1 rep. Come back and do 2. And then 3. Etc.
R
Usually reps
S
Usually sets
X
Times. Sometimes rounds.
SS1 (SS2 etc)
Superset with other superset SS1.
X/Y
Positives over negatives