femtochemistry
- n the branch of chemistry that studies elementary (often very fast) chemical reactions as they occur; the experimental methods are often based on the use of femtosecond laser pulses
femtometer
- n a metric unit of length equal to one quadrillionth of a meter
femtometre
- n a metric unit of length equal to one quadrillionth of a meter
femtosecond
- n one quadrillionth (10^-15) of a second; one thousandth of a picosecond
femtovolt
- n a unit of potential equal to one quadrillionth of a volt (or one thousandth of a nanosecond)
femur
- n the longest and thickest bone of the human skeleton; extends from the pelvis to the knee
fen
- n 100 fen equal 1 yuan in China
- n low-lying wet land with grassy vegetation; usually is a transition zone between land and water
the fens of eastern England
fen orchid
- n small terrestrial orchid of eastern North America and Europe having two nearly basal leaves and dull yellow-green racemose flowers
fen orchis
- n small terrestrial orchid of eastern North America and Europe having two nearly basal leaves and dull yellow-green racemose flowers