noun, noun which may take the genitive case particle 'no'
on the desk; desktop
Literal spatial meaning: something physically on or at a desk. Often used in compounds like 机上の (desktop, on-desk).
机上に書類が山積みになっている。
Documents are piled up on the desk.
机上のパソコンを立ち上げる。
I start up the desktop computer.
noun which may take the genitive case particle 'no'
theoretical; academic; armchair; paper-based; not yet implemented
Figurative use: ideas, plans, or discussions that exist only on paper or in theory, not yet tested or realized. Strongly associated with the set phrase 机上の空論 (armchair theory).
See also: 机上の空論
彼の提案は机上の空論に過ぎない。
His proposal is nothing more than an armchair theory.
机上の計画ではうまくいきそうだが、実際は難しい。
It seems workable as a paper plan, but in reality it's difficult.
Compound of 机 (desk) and 上 (on, above). The figurative sense developed from the idea of something that exists only on a desk (i.e., in theory or on paper) rather than in practice.