The Argos came to terms with the Canadian linebacker Tuesday, more than four years after taking him in the CFL draft. Toronto originally selected the Kingston, Ont., native third overall in 2010 but shortly afterwards he signed as a free agent with the NFL's Kansas City Chiefs.
The six-foot-two, 235-pound Greenwood played three seasons with Kansas City, then joined the Detroit Lions, spending all of last season on injured reserve before being released.
"Just sitting through the meetings, it's a different language," Greenwood said following his first practice with the Argos. "I've got so much to catch up on before Sunday, I'm excited though."
The Argos (7-9) visit the Montreal Alouettes (8-8) on Sunday afternoon in a key East Division contest as the winner will clinch a playoff berth.
"I don't know in what capacity they're going to have me play . . . whatever my role is going to be I'm just going to play," Greenwood said of Sunday's game. "I just need to get into the playbook and sink my teeth into it and just learn that.
"It's a tight race. I just want to come in here and do whatever I can do to help."
Greenwood, 29, played 48 games with Kansas City, registering 35 tackles, primarily on special teams. The six-foot-two 235-pound Greenwood captured the Presidents' Trophy in '09 as Canadian university football's top defensive player.
"The NFL stands for 'Not For Long,' so even my first year I had no idea I was going to make the team," he said. "You really have no idea when your time is going to expire down there.
"I feel like I was blessed to be able to play there, I learned a lot as far as techniques and stuff about the game that hopefully I can bring here and help this team win."
Toronto also released defensive back Harold Mutabola from its practice roster.
"Cory was a top prospect when we drafted him in the first round in 2010 out of Concordia University," Argos GM Jim Barker said in a statement. "He has since spent three years as a professional football player and we are excited to see the type of player he has become and how he will be able to contribute to our team."