Hanging by a thread

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Filipendulous \Fil`i*pen"du*lous\ (?; 135), a. [L. filum a thread + pendulus hanging, fr. pend[=e]re to hang.] (Bot.) Suspended by, or strung upon, a thread; -- said of tuberous swellings in the middle or at the extremities of slender, threadlike rootlets. ...

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
"hanging by a thread," 1864, as if from Latin filum "thread" (see file (v.1)) + pendulus "hanging down" (see pendulous ).

Wiktionary Word definitions in Wiktionary
a. Suspended by, or strung upon, a thread; said of tuberous swellings in the middle or at the extremities of slender, threadlike rootlets.