Covered with wax to make it smooth and shiny, or describing something that has increased in size or intensity.
From Old English 'weax' (noun) and 'waxan' (verb). The verb 'wax' meaning 'to grow or increase' is a separate Old English verb meaning 'to grow,' seen in phrases like 'waxing moon.' Both senses have been in English since ancient times.
The moon 'waxes' (grows) and 'wanes' (shrinks) in a cycle we can see, and ancient people tied so many meanings to it that we have two separate verbs—'wax' meaning to increase, and 'wane' meaning to decrease. Modern poets still use 'waxing eloquent' without thinking about the moon connection!
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