There are many terms for various statistics in baseball, most of them with abbreviations. Below are a list of abbreviations, their full names, and their meanings, as used in the Pitching tables.
Primary Statistics[]
Gm[]
Games played by that player in that year (including part games).
ERA[]
Earned Run Average (calculated by 9*ER/IP )
W[]
Wins credited to that pitcher
L[]
Losses credited to that pitcher
Pct.[]
Winning Percentage (calculated by W/(W+L) )
G[]
number of Games that pitcher appeared in
GS[]
number of Games Started by that pitcher
CG[]
number of Complete Games pitched by that pitcher (start to finish, alone)
SHO[]
number of Shutouts pitched by that pitcher (did not allow the other team to score a run
Inn[]
number of Innings pitched by that pitcher (each out recorded is one-third of an inning, creating .3 - one out recorded, and .7 - two outs recorded)
H[]
number of Hits given up by that pitcher to opposing batters
HR[]
number of Homeruns given up by that pitcher to opposing batters
BB[]
number of Base on Balls (or Walks) given up by that pitcher to opposing batters
SO[]
number of Strikeouts recorded by that pitcher on opposing batters
OBA[]
Opponent's Batting Average - a measure of how well the opposing batters hit that pitcher (calculated by H/OAB)
Secondary Statistics[]
Hld[]
number of Holds credited to that pitcher
GF[]
number of Games Finished by that pitcher
SV[]
number of Saves credited to that pitcher
BS[]
number of Blown Save opportunities charged to that pitcher
SV%[]
the successful Save Percentage - calculated by SV/(SV+BS)
IR[]
number of Inherited Runners (runners already on base when that pitcher was brought into the game)
ISP[]
number of Inherited runners in Scoring Position (runners already on second- and/or thirdbase when that pitcher was brought into the game)
IRS[]
number of Inherited Runners allowed to Score (runners already on base when that pitcher was brought into the game who eventually scored while that pitcher was on the mound)
IRSc%[]
Inherited Runners Scoring Percentage - calculated by IRS/IR
R[]
total number of Runs given up by that pitcher
ER[]
number of Earned Runs given up by that pitcher (runs that would only have scored had defensive errors not been made)
IBB[]
number of Intentional Base on Balls (or Intentional Walks)
HBP[]
number of opponent batters Hit By Pitches
DP[]
number of Double Plays made by the defense when that pitcher was on the mound
Tertiary Statistics[]
OAB[]
number of Opponents' At Bats
DO[]
number of Doubles (a two-base hit) given up by that pitcher
TR[]
number of Triples (a three-base hit) given up by that pitcher
XBH[]
number of Extra Base Hits (hits that were not singles, but doubles, triples and homeruns) given up by that pitcher
OOBP[]
Opponents' On Base Percentage - (H+ BB + HBP)/(OAB+BB+SF+HBP) (SF and HBP are assumed zero if unavailable)
OSLG[]
Opponents' Slugging average - (SI + 2*DO + 3*TR + 4*HR)/OAB
OPRO[]
the opponents' Production - calculated by OOBP+OSLG
WP[]
number of Wild Pitches made by that pitcher
BK[]
number of Balks made by that pitcher
WHIP[]
"Whip" - stands for (Walks+Hits)/Innings Pitched