pe·num·bra /pi-'nəm-brə/ n pl -bras
1: an area within which distinction or resolution is difficult or uncertain
the public-private penumbra
2: an extension of protection, reach, application, or consideration; esp: a body of rights held to be guaranteed by implication from other rights explicitly enumerated in the U.S. Constitution
the First Amendment has a penumbra where privacy is protected from governmental intrusion — Griswold v. Connecticut, 381 U.S. 479 (1965) see also griswold v. connecticut in the important cases section
pe·num·bral /-brəl/ adj
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.