- louse: A small insect parasitic on and sucking the blood of mammals.
- lovable: Amiable.
- low-spirited: Despondent.
- lowly: Rudely.
- lucid: Mentally sound.
- lucrative: Highly profitable.
- ludicrous: Laughable.
- luminary: One of the heavenly bodies as a source of light.
- luminescence: Showing increase.
- luminescent: Showing increase of light.
- luminosity: The quality of giving or radiating light.
- luminous: Giving or radiating light.
- lunacy: Mental unsoundness.
- lunar: Pertaining to the moon.
- lunatic: An insane person.
- lune: The moon.
- lurid: Ghastly and sensational.
- luscious: Rich, sweet, and delicious.
- lustrous: Shining.
- luxuriance: Excessive or superfluous growth or quantity.
- luxuriant: Abundant or superabundant in growth.
- luxuriate: To live sumptuously.
- lying: Untruthfulness.
- lyre: One of the most ancient of stringed instruments of the harp class.
- lyric: Fitted for expression in song.
- macadamize: To cover or pave, as a path or roadway, with small broken stone.
- machinery: The parts of a machine or engine, taken collectively.
- machinist: One who makes or repairs machines, or uses metal-working tools.
- macrocosm: The whole of any sphere or department of nature or knowledge to which man is related.
- madden: To inflame with passion.
- Madonna: A painted or sculptured representation of the Virgin, usually with the infant Jesus.
- magician: A sorcerer.
- magisterial: Having an air of authority.
- magistracy: The office or dignity of a magistrate.
- magnanimous: Generous in treating or judging others.
- magnate: A person of rank or importance.
- magnet: A body possessing that peculiar form of polarity found in nature in the lodestone.
- magnetize: To make a magnet of, permanently, or temporarily.
- magnificence: The exhibition of greatness of action, character, intellect, wealth, or power.
- magnificent: Grand or majestic in appearance, quality, or action.
- magnitude: Importance.
- maharaja: A great Hindu prince.
- maidenhood: Virginity.
- maintain: To hold or preserve in any particular state or condition.
- maintenance: That which supports or sustains.
- maize: Indian corn: usually in the United States called simply corn.
- makeup: The arrangements or combination of the parts of which anything is composed.
- malady: Any physical disease or disorder, especially a chronic or deep-seated one.
- malaria: A fever characterized by alternating chills, fever, and sweating.
- malcontent: One who is dissatisfied with the existing state of affairs.