one, 1 / the first in order, foremost / the beginning / the best / a kind of; one of something / (card games) an ace / unity / the bottom string of a shamisen or other Japanese musical instrument

(mathematics) pure mathematics

each person

a research student (i.e. a visiting or non-matriculating graduate student) / a researcher

researcher

a laboratory

researcher

research association; research society / group of enthusiasts (as may be found in schools, colleges, etc)

research & development; R&D

(education) research project, done by Japanese schoolchildren during summer break, to be presented upon return to school