CD-R disks (CD-Rs) are readable by most plain CD readers, i.e., CD readers manufactured prior to the introduction of CD-R. This is an advantage over CD-RW, which can be re-written but cannot be played on many plain CD readers.
The Collaborative International Dictionary
CD-R \CD-R\ n. [from Compact Disk-Recordable.] a recordable compact disk; a compact disc on which you can write only once and thereafter is read-only.
Syn: compact disc recordable, CD-WO, compact disc write-once.
n. compact disk - read-only or compact disk - recordable; a form of digital media that is based on the use of a laser to read from a plastic disc. It can only be written to once.