L7 (sometimes spelled L-7) has several meanings:

• L7 is 1950s slang for "square", based on the shape made when putting together an "L" made with the left thumb and index finger and a "7" made with the right thumb and index finger.
• L7 is an all-woman punk band whose name is derived from the slang expression.
• The L7 is a British machine gun series.
• The L7 105mm cannon gun is a British-designed turret gun for tanks.
• L-7 is an abbreviation for Landsat 7, an Earth-imaging satellite launched in April 1999.