The Etymology of Ligature
Ligature is a Latinate word that has spread its meaning into half a dozen specialist domains while keeping a single core idea: a binding, a tying-together. The Latin verb ligare (to bind, tie) stands behind ligament (the binding tissue at a joint), league (an association of bound members), oblige (to bind a person toward an action), rely (to bind back), liability, alliance, religion (one possible etymology, from re-ligare, to bind back), and ligature itself. The Late Latin ligatura simply meant a binding, and Middle English borrowed the word around 1400 in that general sense. By the early modern period it had taken on a cluster of specialised meanings. In music, a ligature is a slur joining two notes; in typography, it is two or more letters cast as a single glyph (the fi ligature in fine print, the æ of mediæval, the German ß for double-s); in surgery, it is the thread used to tie off a blood vessel; in forensics, the cord used to strangle. All preserve the original idea: things bound together. The Proto-Indo-European root *leyǵ- (to bind) is the common ancestor of the whole family.