1. (noun) a low triangular area of alluvial deposits where a river divides before entering a larger body of water

• alluvial deposit
• alluvial sediment
• alluvion
• alluvium
• formation
• geological formation

2. (noun) an object shaped like an equilateral triangle

• equiangular triangle
• equilateral triangle

3. (noun) the 4th letter of the Greek alphabet

• alphabetic character
• letter
• letter of the alphabet

1. (noun) the 4th letter of the Greek alphabet

• greek alphabet