Introduction: 
Enterprise keywords are used to tag the documents when uploading the documents in the document library. Enterprise documents can be enabled in both SharePoint lists and libraries. Enterprise keywords - Terms are stored in a non-hierarchical way and available for users to key in which is known as folksonomy (free tagging). In this article we will be seeing how to enable Enterprise keywords for a list using powershell script.
Prerequisites:
- Managed metadata service application should be configured. 
 
 
- Web application should be associated to the Managed Metadata Service Application.
Enable Enterprise Keywords using powershell
To enable enterprise keywords using powershell do the following steps:
- Go to Start => All Programs => Microsoft SharePoint 2010 products => SharePoint 2010 Management Shell. 
 
 
- Run as an administrator. 
 
 
- Run the following script.
 
 $site = Get-SPSite "http://serverName:22222/sites/Test/"
 $web = $site.OpenWeb("BL")
 $list = $web.Lists.TryGetList("dl");
 if ($list -ne $null)
 {
 $field = $list.ParentWeb.AvailableFields["Enterprise Keywords"]
 if ($list.Fields.ContainsField("Enterprise Keywords") -eq $false)
 {
 $list.Fields.Add($field)
 $list.Update()
 write-host $field.Title " added successfully to the list"
 }
 else
 {
 write-host $field.Title  " column already exists in the list"
 }
 }
 else
 {
 write-host $list.Title  " does not exists in the site"
 }
 
 
- Go to the =>Permissions and Management => Enterprise Metadata and Keywords Settings.
 
 
- You could see the "Enterprise Keywords" enabled.