Villa skipper Terry, 36, limped off in the 20th minute of yesterday’s 2-0 defeat to Sheffield Wednesday after breaking a metatarsal bone in his foot.
He is expected to miss up to 10 weeks through injury.
Speaking on Football on 5: The Championship, Morrison said: “Yeah, it’s a big blow to lose John Terry.
“He’s been a catalyst, he’s been strong, he’s been their leader on the pitch and in the dressing room so it’s a massive blow.”
Villa fell behind to Wednesday after just 18 seconds thanks to Adam Reach’s wonder goal.
Jordan Rhodes doubled the Owls’ lead with a tap-in after Terry had limped off.
The absence of Josh Onomah through injury resulted in Steve Bruce switching to a two-man midfield.
And Morrison believes Conor Hourihane struggled without the extra man in the engine room.
“Hourihane was a bit lost in midfield when he was trying to press,” Morrison said.