Allomorphs: Variants of morphemes that are phonologically related, and often phonologically conditioned

• e.g. “a” becomes “an” when placed before a vowel
• e.g. [-s], [-z], [-əz]: Allomorphs of the plural form
• Suppletion: “go” and “went” are not allomorphs because they are phonologically unrelated
• Phonologically Conditioned: Can be predicted using a rule, only the root is stored in memory. e.g. “a” and “an” are phonologically conditioned but “foot” and “feet” are not.
  • Internal Change: Non-phonologically conditioned, must be memorized
• Order matters