septuagenarian

From Latin septuagenarius ("of the number seventy"), from Latin septuāginta ("seventy") +‎ -an

septuagenarian (not comparable)

1. Being between the age of 70 and 79, inclusive. In one's eighth decade.
2. Of or relating to a septuagenarian.

septuagenarian (plural septuagenarians)

1. One who is between the age of 70 and 79, inclusive.
   • 2010, Philip Carr-Gomm, ‎Richard Heygate, The Book of English Magic

     For a ley hunter, local people – particularly the elderly – can be mines of information. Devereux and Thomson recount how they asked a septuagenarian in a remote village the location of an elusive stone, without mentioning the subject of leys: […]

• denarian
• vicenarian
• tricenarian
• quadragenarian
• quinquagenarian
• sexagenarian
• octogenarian
• nonagenarian
• centenarian