The list of verbs is maintained by Microsoft. This formal approach to naming commands greatly assists discovery.

Verbs are words such as Add, Get, Set, and New. In addition to these, we have ConvertFrom and ConvertTo.

The list of verbs is available within PowerShell, as follows:

Get-Verb 

Each verb has a group, such as data, life cycle, or security. Complementary actions such as encryption and decryption tend to use verbs in the same group; for example, the verb protect may be used to encrypt something and the verb unprotect may be used to decrypt.

A detailed list of verbs, along with use cases, is available on MSDN:

https://msdn.microsoft.com/en-us/library/ms714428(v=vs.85).aspx