See: Adjectives and Verbs
Verbs can be used as adjectives; this is called a participle. Some examples of participles are The Flying Dutchman and a loved one. Participles can be either the past-tense form of the verb or the progressive tense (ending in ‑ing). There is no clear way to determine which verb uses which form (although intransitive verbs do not use the progressive tense). Some verbs can use both but each will have a different meaning.
The dog looks like a sleeped baby.
The dog looks like a sleeping baby.
I saw a really bored movie last night.
The participle should be boring; movies cannot be bored.
I saw a really boring movie last night
Make sure you have the right verb form: participles don’t use the present tense.
The frighten girl ran away from the dog.
The frightened girl ran away from the dog.