bioenergybi‧o‧en‧er‧gy /ˈbaɪəʊˌenədʒi $ -oʊˌenər-/ noun [uncountable] 
energy that is obtained from plants or animal waste
energy that is obtained from plants or animal waste- free-falling
- free-floating
- Freefone
- underwent
- underwhelm
- underworld
- underwrite
- underwriter
- Underwriters' Laboratories
- undeserved
- undesirable
- undetected
- undeterred
- undeveloped
- undid
- undies
- undifferentiated
- undignified
- undiluted
- undiminished
- undischarged
- undisclosed
- undiscriminating
- undisguised
- undismayed