What it means
A bookworm is someone who lives half in the real world and half in whatever's happening on the page. They're the mate who'd happily cancel plans for one more chapter, rinses through novels at silly speed, and always has a tottering stack waiting nearby. It's affectionate, sometimes lightly teasing, for a person who's deeply and cheerfully into reading.
Usage examples
"She's been a bookworm since she was five, always three novels deep at once."
"I went full bookworm on holiday and read six books on the beach."
"Don't bother texting him on a rainy Sunday, he's in full bookworm mode with a mug of tea and three chapters left."
"I was such a bookworm as a kid I'd get told off for reading at the dinner table."
Where it comes from
Bookworm is a straight compound of book and worm, built from the image of tiny insects boring into old books. It was being used figuratively in English by the late 1500s for a person buried in reading, and it's stuck around ever since as a warm label for an avid reader.
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