Abbreviated first name found three times on the signed Declaration of Independence

THOS

Think of how "Thomas" might be shortened in 18th-century signatures by three different signers.

This clue looks for a shortened first name that appears three times among the signers of the Declaration of Independence. "Thos" is an old abbreviation for "Thomas," and three signers—Thomas Jefferson, Thomas Stone, and Thomas Heyward Jr.—used that form in their signatures. The word "abbreviated" hints at the shortened version rather than the full name.