Someone or something who aspires to get his/her blood pumpin, adrenal system on full alert, nervous system screting natural stimulants-hormones, Epinephrine, Adrenaline!
Always lookin for that Natural High~Stimulate the mind and body with rush of physical activity or other significant means~
Adrenaline is a catecholamine, a sympathomimetic monoamine derived from the amino acids phenylalanine and tyrosine. The Latin roots ad-+renes and the Greek roots epi-+nephros both literally mean "on/to the kidney" (referring to the adrenal gland, which sits atop the kidneys and secretes epinephrine).
Evil Knievel is an Adrenalinist