The answer to the crossword for the term 'In-Law to Lincoln' is TODD, which is four letters. Mary Todd Lincoln was the wife of Abraham Lincoln, the 16th President of the United States. She was born in Lexington, Kentucky in 1818 and married Lincoln in 1842. Mary Todd Lincoln was a prominent figure in the White House during her husband's presidency and was known for her strong personality and her devotion to her husband.