More boggy; more like a bog with wet, spongy ground that's hard to walk through.
From 'bog' (Irish origin, meaning soft ground) plus comparative suffix -ier. 'Bog' comes from Irish 'bogach' meaning soft.
Comparing bogginess is actually a real problem in Irish and Scottish geography—farmers had to develop whole vocabularies for degrees of wetness because it genuinely affects whether your land is usable.
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