Clue: The length of a meter is based precisely on the amount of light emitted from this

Answer: KRYPTONISOTOPE

Length: 14

---

Similar Clues:

• Post office activity, or a hint to this puzzle's theme (LETTERSORTING with 13 letters)
• Thesaurus offering: Abbr. (SYN with 3 letters)
• Thesaurus offering (abbr.) (SYN with 3 letters)
• Thesaurus offerings: Abbr. (SYNS with 4 letters)
• Offering just the right amount of resistance (ALDENTE with 7 letters)
• Amount offered (BID with 3 letters)
• Offered amount (BID with 3 letters)
• Therapeutic amount (DOSE with 4 letters)
• Offensive, as an amount of money (OBSCENE with 7 letters)
• "Gosh!" (or, based on the starts of starred answers, one who is expert at solving this puzzle's theme?) (GEEWHIZ with 7 letters)