Both stems non-argument-taking [...] Compounds formed of two non-argument-taking stems are probably the most productive sort in English. (11) illustrates a number of these compounds, some of which exist and are frequently used and others of which are, as far as I know, new words: (11) N N compounds: mailman, fire truck, file cabinet, truck-book, baby-finger, squash-bowl; A N compounds: hard hat, wildfire, poorhouse, hard-rock, wild-child, poor-store; N A compounds: sky-blue, girl-crazy, color-blind, branch-brown, wife-blind, gun-crazy; A A compounds: icy-cold, wide-awake, deaf-mute, wet-cold, happy-blind, green-crazy.
- Lieber (2004), Pag. 217