OBLIVIOUS
forgetful, oblivious
(adjective) failing to keep in mind; āforgetful of her responsibilitiesā; āoblivious old ageā
Source: WordNet® 3.1
Etymology
Adjective
oblivious (comparative more oblivious, superlative most oblivious)
(usually followed by to or of) Lacking awareness; unmindful; unaware, unconscious of.
Failing to remember; forgetful.
Source: Wiktionary
Ob*liv"i*ous, a. Etym: [L.obliviosus: cf.F. oblivieux.]
1. Promoting oblivion; causing forgetfulness. "The oblivious pool."
Milton.
She lay in deep, oblivious slumber. Longfellow.
2. Evincing oblivion; forgetful.
Through are both weak in body and oblivious. Latimer.
– Obliv"i*ous*ly, adv.
– Ob*liv"i*ous*ness, n. Foxe.
Source: Webster’s Unabridged Dictionary 1913 Edition