Similar to Windows_Mail
 - CFL条件Courant–Friedrichs–Lewy condition
 - ChaSenChaSen
 - CHECK制約Check constraint
 - ChipCard
 - ChipCard TC-100
 - ChipCard VW-200
 - Chipmunk BasicChipmunk Basic
 - ChordChord (peer-to-peer)
- ChromebookChromebook
 - ChronyChrony
 - CIP4▲1 trends
 - CleanClean (programming language)
- CLIECLIÉ
 - CNS 11643CNS 11643
 - Code ReadingCode Reading
 - Coffee LakeマイクロアーキテクチャCoffee Lake
 - Comet LakeマイクロプロセッサComet Lake
 - Comma-Separated ValuesComma-separated values
- COMMAND.COMCOMMAND.COM
 - Common Management Information ProtocolCommon Management Information Protocol
 - Communication Access Programming Language
 - CompisCompis
 - Compression Attached Memory ModuleCAMM (memory module)
 - CompuServeCompuServe
 - Computer Based TestingElectronic assessment
 - Computer Typesetting System
 - COMPUTEX TAIPEIComputex
 - Conary