A gathering or cluster of people, animals, or things; a group or mass (often read as 'むら' or 'むれ' depending on context).
子どもたちが公園でむらになって遊んでいる。
Children are playing together in a group at the park.
観客は選手の周りにむらを作って写真を撮った。
Spectators formed a cluster around the athlete and took pictures.
データにむらがあると、平均値だけでは全体像を把握しづらい。
If the data are clustered (uneven), it's hard to understand the whole picture using only the mean.
春になると野原に野花がむらをなして咲く。
In spring, wildflowers blossom in clusters across the meadow.