ambit (en)

(noun) the scope, extent, or bounds of something

penumbra (en)

the partially shaded outer region of the shadow cast by an opaque object

recondite (en)

(adjective) hidden from sight; concealed / (adjective) difficult or impossible for one of ordinary understanding or knowledge to comprehend; deep / (adjective) of, relating to, or dealing with something little known or obscure

trammeled (en)

(verb) to catch or hold in or as if in a net; enmesh / (verb) to prevent or impede the free play of; confine