be on to

1. Be aware of or have information about, as in They can't pull that trick again; we're on to them now. [Colloquial; second half of 1800s]

2. Discover something important or profitable, as in The researchers claim they are really on to something big. [Colloquial; mid-1900s]

Informal

To be aware of or have information about: You'll never deceive us again; we're on to you.

Name	Pronounced	Usage
Seyfullah	-	Turkish
Ayla (1)	-	Hebrew
Langdon	LANG-dən	English (Rare)
Tomoko	to-mo-ko	Japanese
Filib	-	Scottish
Tierney	TEER-nee	Irish, English (Rare)