The Greek diphthong "ου" is pronounced like the English "oo" in "food." It is a combination of the vowels "o" and "u," creating a single sound. This diphthong is commonly found in many Greek words, making it an essential part of the language's phonetics. In the Greek alphabet, "ου" is represented by the letters omicron and upsilon. It appears in various contexts, such as in the word καλός (kalós), meaning "good." Understanding how to pronounce and use "ου" is crucial for learners of the Greek language.