We don't have synonyms for flannelettes yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are flannelette.
(n) :
A type of soft, woven fabric, made to imitate flannel by raising or brushing the fibers in the weft. Frequently used in sleepwear, pillows, and bedding.
(n) :
A type of soft, woven fabric, made to imitate flannel by raising or brushing the fibers in the weft. Frequently used in sleepwear, pillows, and bedding.