twelfth letter, Roman form of Greek lambda, which is from the Semitic lamed. The shape of the Roman letter is an early one in Greek, adopted in Italic before it was superseded in Greek by the inverted form which became the Greek lambda. In some words (ladder, lady, laughter, leap, listen, lid) it represents Old English hl-. As "building or extension in the shape of an L" from 1843. As an "alphabetic abbreviation" [OED] of elevated railway, from 1881 (compare el). The Three Ls in nautical navigation were "lead" (for sounding), "latitude" and "lookout."