retention

Compared meaning: the ability to remember things (noun).

比较义项：记忆力，记住事物的能力（名词）。

• memory

  The everyday, general word for the mental ability to remember; can also name one specific recollection ('a memory of...'), and commonly pairs with adjectives like good, bad, short-term.

  日常泛指记忆能力的常用词，也可以指具体的一段记忆（a memory of...），常与 good、bad、short-term 等形容词搭配。

  My grandfather's memory is still sharp even at ninety.

  我祖父即使到了九十岁，记忆力依然很好。

• retention 本词

  A more formal, often academic or medical word focused on how well information is kept and held over time; typically follows a modifier like 'information' or 'memory' and never means one specific recollection.

  更正式，常用于学术或医学语境，强调把信息保持住、记住的能力，通常与 information、memory 等词搭配使用，不能指具体的一段回忆。

  Doctors say poor sleep can reduce information retention in students.

  医生说睡眠不足会降低学生的信息记忆保持能力。

Memory and retention both mean the ability to remember things. Memory is the everyday, general word, and can also mean one specific recollection. Retention is more formal, common in academic, educational, or medical contexts, and focuses on holding information over time, not one specific memory.

这两个词在“记忆力”这个意义上相近，但 memory 是日常泛指记忆能力的常用词，也能指某一段具体的回忆；retention 更正式，常见于学术、教育或医学语境，强调把信息保持住的能力，不能用来指一段具体的回忆。这里不比较 retention 的“（员工）保留率”这一义项。