A low frequency instability in rocket motors in periods of up to several seconds - dangerous in that it can project a vehicle off a launcher and then it becomes an erratic projectile. Found on http://www.aeroconsystems.com/glossary.htm
Chuff noun [ Perh. a modification of chub : confer W. cyff stock, stump.] A coarse or stupid fellow. Shak. Found on http://www.encyclo.co.uk/webster/C/76