Plural of aglet; the small plastic or metal tubes that cap the ends of shoelaces to make them easier to thread.
From French 'aguillette' (needle), which comes from Old French 'aguille' (needle). The word originally referred to needle-like metal tips before becoming applied to shoelace tips.
There's an entire Phineas and Ferb episode about aglets because people genuinely don't know what they're called—it's one of those everyday objects so mundane that most people have never bothered to learn its name, making it perfect for trivia and jokes.
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