Someone
Definition 1 of 2
Pro Tip 1/3
Expectation of Familiarity
Implies the speaker expects you to know or guess who is being referred to. You'll never guess what someone told me!
Pro Tip 2/3
Privacy Respect
Used to omit identity when it should be kept private. Someone special gave me this gift, but I can't say who.
Pro Tip 3/3
Unknown Presence
Indicates the presence of a person whose identity is unknown to the speaker. I heard someone sneaking around outside.