A sysadmin is a system administrator — the person whose job is to keep an organisation's computers, servers and networks running. They set up accounts, install and update software, back up data, watch for problems, and fix things when the system goes down. In a school it is the person you email when you cannot log in; in a company it is the team that keeps the servers alive at three in the morning. The word is a shortening used inside the computing world. It is informal but not rude — sysadmins call themselves sysadmins, and it appears in job adverts, in tech articles and all over the internet. In a formal contract or an official job title you would more likely see the full 'System Administrator'. Note that in the last ten or fifteen years many companies have moved this work to roles called 'DevOps engineer' or 'SRE' (site reliability engineer), so 'sysadmin' can sound slightly old-school to younger people in the industry — still perfectly correct, but it suggests traditional server-room work rather than cloud automation. You will also see it written 'sys admin' or 'sys-admin'; one word is the most common.

系統管理員（俗稱「系統管理者」、口語常直接說「MIS」或「IT 的人」）。台灣公司裡負責這件事的部門通常掛名 MIS 或資訊部，學生聽到「找 IT」指的就是這種人。