一叢[hitomura] copse
稲叢[inamura] stack of rice straw
叢がる[muragaru] to swarm
叢雨[murasame] passing shower
叢時雨[murashigure] autumn shower

叢書[sousho] series (of publications)
叢生[sousei] dense growth
叢談[soudan] collection of stories
叢氷[souhyou] pack ice
叢立ち[soudachi] standing in a group

ストックホルム症候群[sutokkuhorumushoukougun] Stockholm syndrome
亜群[agun] subgroup
一群[ichigun] group
一群れ[hitomure] group
可換群[kakangun] Abelian group

魚群[gyogun] school of fish
繰込み群[kurikomigun] renormalisation group (physics)
群がる[muragaru] to swarm
群れ[mure] group