In grammar, intransitive describes a verb that doesn't need an object to complete its meaning. When you use an intransitive verb, the action doesn't pass to anything or anyone else.

Think about the sentence “The dog barked.” The verb barked is intransitive because the action is complete on its own. The dog just barked. You don't need to say what the dog barked at. Compare this to “The dog chased the cat.” Here chased is a transitive verb because the action passes from the dog to something else (the cat). You can't just say “The dog chased” and leave everyone wondering what got chased.

Some verbs are always intransitive: sleep, arrive, fall, and laugh. You can't sleep or arrive something. Other verbs can work both ways. “She runs” uses runs intransitively, while “She runs a business” uses it transitively.

When you see intransitive in a dictionary entry, it tells you the verb stands alone. It doesn't cross over to affect an object.