Template
Very generally, a template is a process that transforms content in another format.
Most often, a template referr to a mixture of presentational markup (usually HTML) and other templating code used to prepare content objects for delivery.
Multiple templates can be applied to the same object to produce different presentations. A template is normally stored as a file in a source code management system and managed as code. There will normally be at least one template per content type.
In some CMS (for example: Sitecore), the term "content template" (or even just "template") is used to refer to content types. In those systems, templates (as defined here) have a different name or modifier ("renderings," "rendering templates," or "output templates" for example).
"Template" is occasionally used as a verb to mean the create of a template to apply to a content object: "We need to template this content type."