writable
Computing term describing a storage medium or file that can be written to, such as a writable CD-ROM or a writable disk image.
This CD-R is writable.
Mount a writable file system.
読み取り専用 means read-only, the opposite of writable.
書き込み禁止 means write-protected, preventing writing even if the medium is inherently writable.
Compound of 書き込み (writing) and 可能 (possible).