noun
Etymology: Middle English fetherbed, from fether feather + bed (I) — more at feather
1.
a. : a feather mattress
b. : a bed having a feather mattress
2. : a markedly easy and comfortable state or position : sinecure
3. : a bed often formed in pools and shallow lakes by the crowded growth of stoneworts ; also : a stonewort of the genus Chara