1Interchangeability; the ability to be exchanged or substituted between items (e.g., parts).
このパーツは旧型と互換があるため、買い替えが容易だ。
These parts are interchangeable with the old model, so replacement is easy.
メーカーは互換部品の提供を表明した。
The manufacturer announced they will provide interchangeable parts.
2In mathematics: transposition or the conceptual swapping of elements/order (used in certain contexts).
数学の議論で互換を考える場合、要素の位置を入れ替えても性質が保たれるかを調べる。
When considering transposition in math, one examines whether properties remain when elements' positions are swapped.
3Compatibility (e.g., hardware/software): being compatible or interoperable with another system.
このメモリは新しいマザーボードと互換性がある。
This memory is compatible with the new motherboard.
互換インクを使えば純正品より安く印刷できる場合がある。
Using compatible (third-party) ink can sometimes print cheaper than genuine cartridges.