largely

Compared meaning: mostly, to a great extent (adverb).

比较义项：主要、大多，指“大部分情况下”或“很大程度上”（副词）。

• mostly

  Emphasizes that most of a group, time, or amount is a certain way; common in everyday, informal descriptions of composition or frequency.

  强调某群体、时间或数量的大部分是某种情况；常用于日常、口语化地描述构成或频率。

  The audience was mostly made up of young students and teachers.

  观众大多是年轻学生和老师。

• largely 本词

  Emphasizes the main cause or extent of a result, often paired with 'due to' or 'because of'; slightly more formal than mostly.

  强调结果的主要原因或程度，常与 due to、because of 搭配使用；语气比 mostly 略正式。

  The project's success was largely due to good teamwork.

  这个项目的成功在很大程度上归功于良好的团队合作。

Mostly and largely both mean 'for the most part'. Largely often points to the main cause of a result, often with 'due to' or 'because of'. Mostly is more everyday and describes amount or frequency, like most of a group or most of the time.

两词都表示“大部分、大体上”，但 largely 更强调原因或影响的主导性，常与 due to、because of 等搭配说明主因；mostly 更偏重数量或频率上的“大部分时候／大部分成分”，语气更平实、口语化。两词在此均只比较这一义项，未涉及其他用法。