poor friend; bad friend / (humorous) good friend; partner in crime

luxurious travel

private

核保有国: nuclear power

万有引力: universal gravitation

固有関数: eigenfunction

核融合炉: fusion reactor

"sake" radical (さけづぐり) / "bird of the zodiac" radical (ひよみのとり, とりへん) / rooster (tenth sign of the Chinese zodiac)

a person with lithe movements / kind (adj.), favor / good, excellent, surpass, superior / the best possible grade on school results / rich, wealthy / a sufficient amount for a certain thing

again, as well / and / also