soft spongelike central cylinder of the stems of most flowering plantsthe choicest or most essential or most vital part of some idea or experience
同义词：kernelsubstancecorecenteressencegistheartheart and soulinwardnessmarrowmeatnubsumnitty-gritty
v.remove the pith from (a plant)
英汉双解大词典
pith/pɪθ/
1.
N-UNCOUNT（不可数名词） Thepith of an orange, lemon, or similar fruit is the white substance between the skin and the inside of the fruit. (橙、柠檬或相似水果的果皮和果肉之间白色的)髓 [usu 'the' N]