细语 (xì yǔ) is a noun referring to a low, soft, and intimate form of speech, especially between lovers or close partners. It often appears in phrases like 窃窃私语 ('to whisper in a low voice') or 枕边蜜语 ('pillow talk'). Although the English gloss includes verbs like 'speak softly' and 'whisper', the word itself functions as a noun — you 'have' or 'exchange' 细语, not '细语 someone'. Use it to describe confidential or tender conversations that are barely audible.