1. [mid-19C+] to realize, to notice, to recognize; thus tumble to
2. [mid-19C+] to agree (to), to take a liking (to).
3. [mid-19C+] (UK Und.) to understand.
4. [mid-19C+] (UK Und.) to alert, to make someone suspicious.
5. [20C+] (US Und.) to be arrested.
6. to listen.
7. [1950s+] to unmask, to recognize as fake.
1. [mid–late 19C] to involve oneself energetically or enthusiastically.
2. [mid-19C+] (US) to discover, to become aware of.