pegamoid
/ˈpɛɡəmɔɪd/noun
A kind of waterproof facing or substance used in upholstery, bookbinding, etc.; (hence also) imitation leather or other waterproof material.
adjective
Made of pegamoid. Also figurative : impassive, impervious, not susceptible to emotion.
Origin
Late 19th century. Origin uncertain; perhaps from the name of the PegamoidCo., although it is unclear whether the company may not have been named after the material; for the further etymology perhaps compare Spanish pegamento glue, adhesive, or ancient Greek πηγνύναι to fix, fasten.