Merriam-Webster Collegiate Dictionary - ligature

 noun  Etymology: Middle English, from Late Latin ligatura, from Latin ligatus, past participle of ligare to bind, tie; akin to Albanian lidh I tie  Date: 14th century  1.  a. something that is used to bind; specifically a filament (as a thread) used in surgery  b. something that unites or connects ; bond  2. the action of binding or tying  3. a compound note in mensural notation indicating a group of musical notes to be sung to one syllable  4. a printed or written character (as ? or {Forte}) consisting of two or more letters or characters joined together