the ground / earth, dirt, mud, soil / the earth (as opposed to the heavens) / the ground or bottom of something (as of a price range)

place, area

(colloquial) current boyfriend

everything

(slang) Alternative form of 彼氏 (kareshi, “boyfriend”)

everyone, one and all

research & development; R&D

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

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

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