I feel like doing 1 positive thing today, so here it goes... 8)
CEC - Canadian Experience Class
AOR - Acknowledgment of Receipt
MR - Medical request
RPRF - Right of permanent residence fee
PPR - Passport request
COPR - Confirmation of permanent residence
Counterfoil - Visa attached to passports of non-visa exempt countries
RFO - Ready for Officer
PCC - Police clearance certificate
IELTS - International English language testing service
CELPIP - Canadian English language proficiency index program
NOC - National occupational classification
OB - Operational bulletin
IRPA - Immigration and Refugee Protection Act
eCAS - Electronic client application status
GCMS - Global case management system
VO - Visa officer
CIO - Centralized Intake Office
CPPO - Case Processing Pilot Ottawa
BOWP - Bridged open work permit
PGWP - Post graduation work permit
WP - Work permit
Eligibility - CIC evaluation of your compliance with all requirements (pass or fail)
Medical - Applicants medical exam when requested by CIC
Criminality - PCC sent with application, including CIC independent checks and RCMP (when requested)
Security - Checks completed by CSIS
But as Omshri said, in the future, you can always search and find almost everything on the forum. Best of luck!