This document outlines 5 main rules for making words plural in English: 1. Most words form the plural by adding 's'. 2. Words ending in 'ch', 'sh', 's', 'ss', 'x' or 'z' form the plural by adding 'es'. 3. Words ending in 'o' preceded by a consonant form the plural by adding 'es', with some exceptions. 4. Words ending in 'y' preceded by a consonant change the 'y' to 'i' and add 'es' to form the plural. 5. Words ending in 'ay', 'ey', 'iy', 'oy' and 'uy' form