senior citizen (n.)

• ancient
• centenarian
• dotard
• elder
• gaffer
• geezer
• gramps
• grandfather
• graybeard
• nonagenarian
• octogenarian
• old-timer
• older
• oldster
• pantaloon
• patriarch
• pensioner
• presbyter
• senior
• septuagenarian
• sexagenarian
• veteran