To find out all alias names associated with a given command, filter the alias list by its definition property. The following command lists all aliases that point to the Get-ChildItem cmdlet:
Get-Alias | Where-Object { $_.Definition -eq 'Get-ChildItem' }
To get a comprehensive list of all Cmdlets and their aliases, group the result by Definition:
Dir alias: | Group-Object Definition | Sort-Object Count -descending