ou/ow diphth

Rule Core

The ou/ow diphthong most commonly represents /aʊ/, a true gliding vowel moving from a low, open position to a higher, rounded one. ow is highly consistent with /aʊ/ (now, town), while ou is variable: it may signal /aʊ/ (out, loud) or a monophthong such as /uː/ or /ʊ/, especially in French-derived vocabulary.

Articulation Guide

Begin with a relaxed jaw and open mouth, tongue low and central. Glide smoothly as the tongue rises and retracts; the lips narrow into light rounding. Airflow remains continuous—avoid breaking the sound into two vowels.

Word Analysis

• boulevard: initial ou = /uː/, reflecting French origin.
• coup: ou = /uː/ only; no diphthongal movement.
• coupon: varies by dialect—/ˈkuːpɒn/ or /ˈkjuːpɒn/—never /ˈkaʊ-/.

Pitfall Avoidance

Do not overgeneralize ou = /aʊ/. Check etymology and stress patterns. Note that ow tends to appear word-finally, whereas ou often occurs medially with multiple pronunciations.