american maidenhair fern: hardy palmately branched North American fern with divergent recurved branches borne on lustrous dark reddish stipes
maidenhair: any of various small to large terrestrial ferns of the genus Adiantum having delicate palmately branched fronds
iodine-131: heavy radioactive isotope of iodine with a half-life of 8 days; used in a sodium salt to diagnose thyroid disease and to treat goiter