気体(きたい)

気体(きたい) is the scientific term for gas as a state of matter, referring to a substance whose molecules move freely and expand to fill any container.

STATES OF MATTER:

• 固体(こたい): solid
• 液体(えきたい): liquid
• 気体(きたい): gas

COMMON PATTERNS:

• 気体(きたい)になる: to become a gas (change of state)
• 気体(きたい)の状態(じょうたい): gaseous state
• 気体(きたい)を発生(はっせい)させる: to generate a gas

SIMILAR WORDS:

• 気体(きたい): gas (scientific, academic contexts)
• ガス: gas (loanword, everyday use; also cooking gas, natural gas)
• 蒸気(じょうき): steam, vapor (specifically the gaseous form of water or other liquids)

REGISTER:
Used primarily in science, education, and technical writing. In everyday life, ガス is more common.