Plural of footbath; multiple basins for bathing feet or instances of bathing feet.
Simple plural of 'footbath' using the standard English '-s' ending, with the 'th' sound becoming a 'th' or 'dh' in the plural pronunciation.
English pluralization seems simple until you notice the 'th' in 'baths' changes to a 'dh' sound in 'footbaths'—this voicing pattern is a ghost of Old English grammar rules that most people follow unconsciously.
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