The decade of the 1870s, 1970s, etc.
The decade of one's life from age 70 through age 79.
(temperature, rates) The range between 70 and 79.
From or evoking the 71st through 80th years of a century (chiefly the 1970s).
I know the theme of the school dance is "The 1970s" but is covering the walls, floor, and ceiling with tie-dye too seventies?