eighties
Concise Oxford English Dictionary © 2008 Oxford University Press:
eighty/ˈeɪti/
▶cardinal number (pl. eighties) equivalent to the product of eight and ten; ten less than ninety; 80. (Roman numeral: lxxx or LXXX)
– derivatives
eightieth ordinal number,
eightyfold adjective & adverb.
eightieth ordinal number,
eightyfold adjective & adverb.
'eighties' also found in these Oxford entries:

