Lacking personal depth and substance; conceited, vain, shallow, superficial.
Having length, but no width, height or depth.
Lacking depth or believability; flat.
Reasonably large in number or amount.
Having a low probability of occurring by chance (for example, having high correlation and thus likely to be related).
Having a covert or hidden meaning.
Having a noticeable or major effect.
Signifying something; carrying meaning.
That which has significance; a sign; a token; a symbol.