1. the numbers from 70 to 79, especially when referring to temperature or age
2. the decade from 1970 to 1979

Examples

• The temperature reached the mid-seventies today.
• My grandmother is in her seventies but still very active.
• The seventies were known for disco music and bell-bottom jeans.
• Fashion from the seventies is making a comeback.
• He’s somewhere in his seventies, maybe seventy-five or seventy-six.
• The seventies saw major changes in American culture.
• It’s supposed to be in the low seventies this weekend.