Present participle of guggle; the action of making a bubbling sound, or an adjective describing something that makes such sounds.
Formed from guggle with the addition of '-ing' suffix, which creates present participle forms and nominalizations from verbs.
The '-ing' suffix is one of English's most versatile tools—it turns any verb into a noun or ongoing action, which is why a bubbling water fountain is both 'guggling' (what it does) and 'the guggling' (we can talk about it as a thing).
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