How to say "solid-state" in Japanese

• 固体こたいJLPT N1approx.Common
  no-adjectiveThe common word for a solid: a body or mass of matter in the solid state, as opposed to a liquid or a gas. It also covers the adjectival 'solid-state' of scientific terminology.
  固体こたいが解とけると液体えきたいになる。↗

  When a solid melts, it becomes liquid.
• ソリッドステート
  no-adjectiveThe loanword, a direct katakana borrowing of the English term, used mainly in technical fields such as electronics. It is the less common of the two, so 固体 remains the default in general writing.

For a solid as a state of matter, 固体 is the common word; for the adjectival 'solid-state' of science and technology, either word can serve, though 「ソリッドステート」 is the less common loanword.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 固体こたいsolid (body)
• ソリッドステートsolid-state