The Tooltip Glossary eCommerce edition can integrate Merriam Webster Dictionary or Thesaurus, each of them requiring its own API key that needs to be obtained.
To start working with Merriam Webster Dictionary API you first need to set the plugin setting to support MW content in the term page or the tooltip.
For each term page the metabox can be defined to show or not to show the MW content while overriding the plugin settings:
https://www.cminds.com/wordpress-plugins-knowledge-base-and-documentation/?hscat=6-cm-tooltip