Definition

1. Noun:
   • An architectural ornament in the form of three arcs arranged in a circle: A stylized design resembling a three-lobed leaf or flower, commonly used in Gothic architecture, especially in windows and stone tracery.
   • A plant of the genus Trifolium: A herbaceous plant, such as clover, typically having leaves with three leaflets.
   • Any of several Old World herbs of the genus Medicago: A plant, such as black medick, with small flowers and trifoliate (three-part) compound leaves.

Examples of Usage

• Noun (Architecture):
  • The Gothic window was decorated with an intricate stone trefoil.
  • Trefoils and quatrefoils are common motifs in medieval church architecture.
• Noun (Botany - Trifolium):
  • The field was covered in white trefoil, also known as clover.
  • Farmers often plant trefoil as a forage crop for livestock.
• Noun (Botany - Medicago):
  • The yellow trefoil (Medicago lupulina) is common in pastures.

Advanced Usage

• "Trefoil arch": An arch with a cusped intrados (inner curve) shaped like a trefoil.
  • The trefoil arch above the doorway is a fine example of 13th-century craftsmanship.
• "Trefoil knot": In mathematics, the simplest example of a nontrivial knot, resembling the three-lobed shape.
  • The trefoil knot is a fundamental concept in knot theory.

Variants and Related Words

• Quadrifoil (n): An ornamental shape with four lobes or leaves.
• Cinquefoil (n): An ornamental shape with five lobes or leaves; also a plant of the genus .
• Trifoliate (adj): Having three leaves or leaflets.
  • The plant is easily identified by its trifoliate leaves.

Synonyms

• Clover (n): A common name for plants of the genus .
• Shamrock (n): A young sprig of clover, used as a symbol of Ireland.
• Three-leaved (adj): Having three leaves (descriptive, not a direct synonym for the ornament).

Related Phrases

• "In trefoil": A heraldic term describing a charge arranged in a group of three, like a clover leaf.
  • The family crest featured three martlets in trefoil.

Noun

1. an architectural ornament in the form of three arcs arranged in a circle
2. a plant of the genus Trifolium
3. any of several Old World herbs of the genus Medicago having small flowers and trifoliate compound leaves