Ligatures

About

"In printing and writing, a type or character consisting of or representing two or more letters or characters united. In type-founding the ligatures fl, fl, ff, ffi, ffl are made on account of the kern or overhanging top of the letter f. Six others were formerly made with the similarly shaped long s, now disused—fb, fh, fi, fk, fl, and ft; and there was also a ligatured ct (εt). A still larger number of ligatures were used in old fonts of Greek type, all of which are now generally discarded. In medieval cursive or minuscule manuscripts, especially of Greek, ligatures are very numerous, and in the earlier printed editions about fifty such characters are of frequent occurrence. Some of the Greek ligatures and of the elements composing them seem to have originated in tachygraphic or shorthand characters. See tachygraphy."

--The Century Dictionary and Cyclopedia