Combining the characters
纏 [chan] - meaning "to twine" (v), "rope/string" (n), "to be pestered/entangled" (v)
綿 [mian] - meaning "continuous" (adj), "to entwine" (v), "wool/cotton floss" (n)
to mean "tangled so much you cannot break away", "endlessly continuous", "enwrapping in a way that evokes emotion"
1. of an emotion or illness, to be lingering, pestering, inescapable, or clinging, sometimes in a troubling way
Examples: expand
纏綿病榻 = bedridden with a lingering illness (idiom)
思念很纏綿 = [these] thoughts don't fade away / [these] thoughts are the kind to linger
鄉思纏綿 = troubled by (lingering) homesickness
纏綿不斷 = moreish / endlessly lingering
2. of a singing voice, to be so enthralling that it evokes emotion (often grouped with 5.)
歌聲是那樣的柔和纏綿 = the singing voice was very gentle and sweet, [the type to move someone]
綿纏動人的歌聲 = an incredibly emotionally moving singing voice
3. the sweetness, tenderness, or fondness of emotions, so tightly wound that the involved people cannot or will not break apart
情意纏綿 = [these] emotions are tender
纏纏綿綿 = deep affection
情意纏綿的談話 = a quiet talk / an intimate conversation
4. (slang) have sex, make love
一夜纏綿 = make love over one night
情侶纏綿 = have sex with one's sweetheart
5. to be poignant and incredibly sentimental, sometimes to the point of being saccharine or soppy
纏綿悱惻 = exceedingly sentimental / heartbreakingly beautiful / full of pathos (idiom)
纏綿的愛情故事 = a sentimental love story