When the –ed breaks the rules
Some adjectives end in –ed and are pronounced as having an extra syllable. In other words, they do not follow the general rule for pronouncing the –ed ending.
Below are some adjectives that are derived from verbs and whose –ed endings are pronounced as an extra syllable:
dogged (a dogged persistence)
legged (one-legged; three-legged)
Sometimes, only the context can help you determine which one should be used, compare :
a) He blessed /t/ the kid vs. The blessed /id/ virgin.
b) This is learned /d/ behavior vs. He is a learned /id/ man.
The following list is a more extensive one and is meant to help you remember which words are pronounced with the extra /id/ syllable:
naked, wicked, wretched (a wretched beggar), rugged (a rugged country), crooked, sacred, aged (an aged person), jagged, ragged (a ragged beggar),
The same happens when –ed is used in the formation of adverbs:
Allegedly, arruredly, supposedly, resignedly, resolvedly.