Not a standard dictionary word—possibly a name or informal variant of 'fill.'
If interpreted as a name, derived from Greek 'Philip' meaning 'lover of horses.' If a dialectal variant of 'fill,' would share roots with Old English 'fyllan.'
As a name, Phill/Phil has been popular for centuries, but as a standalone dictionary word it doesn't have standard meaning. Many word lists include it only as a proper name or very informal speech.
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