关于“落伍”的英语翻译，综合多个权威来源的信息如下：

一、核心翻译

基本表达

- behind the times：

表示因观念、技术等落后于时代潮流，例如：

> The company's products are outdated； we're behind the times.

- outdated：强调事物本身过时，例如：

> This software is outdated and needs an upgrade.

动作性表达

- fall behind：

侧重在发展过程中被他人超越，例如：

> The company fell behind its competitors due to lack of innovation.

- drop behind：强调从队伍中落后，例如：

> The project team started to drop behind schedule.

二、使用场景对比

| 中文表达 | 英语表达| 适用场景 |

|----------------|-------------------------|--------------------------------------------------------------------------|

| 落伍 | behind the times| 形容观念、技术等落后于时代 |

| 落伍 | outdated| 形容事物本身过时，需被替换 |

| 掉队 | fall behind | 强调在发展过程中被超越 |

| 掉队 | drop behind | 强调从队伍中落后，常与进度、排名等搭配 |

三、例句参考

形容技术落后

> The car's technology is really outdated； it's like driving a horse and carriage in the 21st century.

形容观念陈旧

> Her ideas are still behind the times； we need to think more innovatively.

描述进度滞后

> The project is falling behind the timeline, we need to speed up the work.

建议根据具体语境选择表达：若强调“过时”属性用 outdated，若强调“落后于进程”用 fall behind或 drop behind，若强调“被时代淘汰”用 behind the times。