People say "pageview" as if every tool agreed. They agree on the idea and not on the edges. The idea is: a page was loaded in a browser, and something recorded that load. The edges are caching, single-page apps, and whether your widget was on the page.
What gets counted
In a typical analytics tag, the count goes up when the tag runs on a full page load. A reload runs the tag again, so it is another pageview. Opening the same article in two tabs is two. A single-page app that swaps the URL without a reload only counts a pageview if the tag is told about the swap. Many sites forget that and undercount.
A server log counts the request for the HTML. It also counts requests for CSS, images, and API calls if you do not filter them. That is why a raw log line count is not a pageview. You have to decide which URLs are pages.
MapMyVisitors counts loads of the widget. If the widget is in the template of every page, that count is close to a pageview of those pages. If the widget is only in the footer of the homepage, the count is homepage loads. The unit is explained in what a visitor counter counts. The glossary entry pageview is the one-sentence version.
What a pageview is not
It is not a unique visitor. Ten pageviews can be one person reading ten pages or ten people reading one. It is not a session either. A session is the product's grouping of those pageviews into a visit.
Do not divide pageviews by visitors and call the result "engagement" unless you know both numbers came from the same tool and the same dates. Mixing a counter with a unique-visitor number from somewhere else produces a ratio that does not describe anyone.
How to talk about it
Name the tool and the dates. "About 4,000 pageviews in MapMyVisitors in March" is a clear sentence if the widget is on the pages you mean. "4,000 pageviews" with no tool is a number the next person cannot check. If you need people rather than loads, say so and use a product that actually tries to count people. The counter will not become that product because you used a different word.
