UNDERFELT
Meaning of UNDERFELT in English
un ‧ der ‧ felt /ˈʌndəfelt $ -ər-/ BrE AmE noun [uncountable]
British English soft material that you put between a ↑ carpet and the floor
Longman Dictionary of Contemporary English.
Longman - Словарь современного английского языка.
2012