原来 (yuánlái) means "originally" (similar to 本来) or "former". It can also mean "all along", and can be used to indicate a sudden realization of something previously unknown, a bit like "so it's been like that all along, how could I not have realized?".

Structure
原来 + Noun/Adjective/[verb phrase]

Examples

Nǐ yuánlái de fāxínɡ hěn kěài, jiǎn le tài kěxī le!
1. 你 原来 的 发型 很 可爱, 剪 了 太 可惜 了!
Your original hairstyle was very cute. It's a shame that you cut it.

Wǒ fāshì wǒ yuánlái shénme dōu bú zhīdào, tā jīnzǎo cái ɡàosu wǒ zhèɡe xiāoxi。
2. 我 发誓 我 原来 什么 都 不 知道,她 今早 才 告诉 我 这个 消息。
I swear: I didn't originally know anything about it. She just told me this news this morning.

Yuánlái kēxuéjiā yǐwéi jīɡuānɡ méiyǒu duōdà yònɡchù, kě tā què chénɡwéi le 20 shìjì zuì zhònɡyào de fāmínɡ zhīyī。
3. 原来 科学家 以为 激光 没有 多大 用处,可 它 却 成为 了 20 世纪 最 重要 的 发明 之一。
Originally, scientists didn't think lasers had much use, but it is one of the 20th century's most important inventions.