trunk, stem, stalk...

executive secretary, coordinator, organizer...

management, (executive) staff, leaders...

Shinkansen, bullet train

foundation, root, basis...

main line, trunk line

superintendence, supervision, administration

mainstay, nucleus, key

chief editor, managing editor, manager...

main current

Japanese timber bamboo (Phyllostachys bambusoides), giant timber bamboo, madake...

natural note (i.e. not sharp or flat), natural tone

stem (non-inflecting part of a word), word stem

ability

hemp reed, hemp stalk

trunk, shaft

shaft of an arrow (usu. made of thin bamboo), cornetfish

body, trunk, torso...

skeleton, structure, build

brain stem

remnants of a bean plant, beanstalks and pods, bean husk

trunk (of the body), soma

caudex (of a plant)

dried taro stem

stem (of a note)

penis, dick

board of governors

chief secretary (usu. of a party), secretary-general

board of directors

stem cell