also: アドウエア
noun
adware
Computing term for software that automatically displays advertisements, often bundled with free programs.
無料ソフトをインストールしたら、アドウェアが一緒に入ってきた。
When I installed the free software, adware came along with it.
Malware is a broader category of malicious software; adware is a specific type that may or may not be malicious.
Loanword from English 'adware', a blend of 'advertisement' and 'software'.