What might a pilot mean by "uncontrollable"?
"Uncontrollable" is a technical term (actually, in literature it's more often called "loss of control"). It means the aircraft is not responding to at least one normal command. Be it elevator or ailerons or rudder etc.

Really, really good AND lucky pilots can sometimes still control aircraft that's uncontrollable. Either by using another control surface to influence the control desired (eg. by using rudder to get out of a bank) or by using non-primary surfaces like trim tabs or flaps.

When no control input will influence what the aircraft is doing then it's called total loss of control (or totally uncontrollable).