v.tr. (-lying; past -lay; past part. -lain) 1 (also absol.) lie or be situated under (a stratum etc.). 2 (also absol.) (esp. as underlying adj.) (of a principle, reason, etc.) be the basis of (a doctrine, law, conduct, etc.). 3 exist beneath the superficial aspect of.
[ OE underlicgan (as UNDER-, LIE(1)) ]