Led - LED

The word led (in lower case letters) is the past tense of the verb 'to lead'. There is a note about that at Lead - led.

In upper case, however, LED is a relatively new word, introduced in electronic engineering and such technologies. It is an acronym, standing for 'Light Emitting Diode: a form of transistor that responds to the passage of electric current by emitting light. It is best pronounced as a series of letters: 'ell ee dee', IPA: /ɛl iː diː/. Many of the little lights that show (or flash) green or red on computer equipment and other pieces of modern technology are made visible by the use of LEDs.