カスタム

カスタム is the English loanword "custom" used in the sense of "customized." In Japanese it freely combines with する to form a verb (カスタムする = to customize) and shows up in many compound terms.

Common collocations

• カスタムする: to customize
• カスタム化(か): customization (the process)
• カスタム設定(せってい): custom settings
• カスタムメイド: custom-made (commonly used for tailored clothing, custom-built PCs, etc.)
• カスタムパーツ: custom parts (esp. for cars, bikes, PCs)
• カスタムカー: customized car
• フルカスタム: fully customized (a build with extensive modifications)

Similar / related terms

• カスタマイズ: customization — the longer-form loanword, common in software contexts (e.g., UI customization, browser settings); largely interchangeable with カスタム but a touch more formal in IT writing.
• 改造(かいぞう): modification, conversion — a stronger native term often used for substantial mechanical or structural alteration (cars, motorcycles, game consoles), and sometimes carrying a borderline-illegal connotation depending on the domain.
• 特注(とくちゅう): custom order; specially ordered — used for one-off or made-to-order items (e.g., 特注(とくちゅう)の家具(かぐ) "custom-ordered furniture").
• オーダーメイド: made-to-order — closely related to カスタムメイド but emphasizes the ordering process rather than the modifications.

Usage

• カスタム is informal in feel; product marketing copy and IT documentation often prefer カスタマイズ in formal sentences ("カスタマイズが可能(かのう)です" rather than "カスタムが可能(かのう)です").
• For deeper modifications that change the original specs (engine swaps, hardware replacements), 改造(かいぞう) or カスタム are both used, with 改造(かいぞう) sounding more technical or, in some contexts, more illicit.