1. Botany:
* A trefoil is a three-leafed plant, most commonly referring to clover (genus Trifolium).
* Some other plants with three leaves are also called trefoils, like shamrock (Oxalis acetosella) or the wood sorrel (Oxalis spp.).
2. Geometry/Heraldry:
* A trefoil is a three-lobed geometric shape, often found in architecture and heraldry. It can be symmetrical or asymmetrical, with rounded or pointed lobes.
* It's often used as a decorative element in Celtic art and symbolism.
3. Knot Theory:
* In knot theory, a trefoil knot is the simplest nontrivial knot. It's a closed loop that forms three crossings.
4. Other:
* The term trefoil can sometimes be used metaphorically to describe something that has three parts or aspects.
To determine the most accurate definition, consider the context in which you encountered the word "trefoil."