Abbreviation of シンパサイザー. Used for someone who sympathizes with a political group or movement, especially communist or union causes, without being a formal member.
See also: シンパサイザー
He became a sympathizer of that movement during his student days.
He is a Communist Party sympathizer, but not a formal member.
組合のシンパが集会に参加した。
Union sympathizers attended the rally.
その団体は地道な活動でシンパを増やしていった。
The group steadily gained more sympathizers through its grassroots activities.
Abbreviation of シンパサイザー, from English 'sympathizer'.