1. An initialism for "out to lunch," literally meaning having left one's home or workplace to get lunch. Used primarily in informal written communication. I received an automated email from the accountant saying that she was OTL.

2. An initialism for "out to lunch," figuratively meaning (by extension from Definition 1) not connected or in touch with the real world; absentminded, uninformed, or cognitively impaired. Used primarily in informal written communication. Jim's been a bit OTL lately, don't you think? I kept trying to ask her about how the meeting went, but she was OTL the whole time. It must not have gone well, because her mind was definitely elsewhere.