ankle-deep, birdbrained, birdwitted, cursory, depthless, epidermal, featherbrained, flighty, fluffy, frivolous, frothy, jejune, knee-deep, light, not deep, on the surface, shallow-headed, shallow-minded, shallow-pated, shallow-rooted, shallow-witted, shallow, shoal, skin-deep, slight, superficial, surface, thin, trivial, volatile