As an expert in linguistics and idioms, I can explain that the phrase "pennywise pound foolish" is a play on the more common idiom "penny wise and pound foolish." This idiom is used to describe someone who is careful with small amounts of money but careless with larger amounts, failing to see the bigger financial picture.

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This phrase alludes to British currency, in which a pound was once worth 240 pennies, or pence, and is now worth 100 pence. The phrase is also occasionally used for being very careful about unimportant matters and careless about important ones.read more >>