When we do a global search for 'desktop', it returns results which actually don't contain the term desktop in meta, short_description, name, description fields of the catalog item.
Any support release
The behavior is seen because of a field on catalog item 'mobile_picture_type' which has default value of 'use_desktop_picture'. In the dictionary entry for this field, there is no attribute no_text_index=true. So this field is being used in text search and returns records which have mobile_picture_type set to use_desktop_picture.
This is the expected behavior with global search. If the intended behavior is not to return the results that have 'use_desktop_picture' in 'mobile_picture_type' and just want to return the results based on description, meta, name, short description only, add the attribute no_text_index=true for mobile_picture_type dictionary record on sc_cat_item table.
Once this is added, regenerate the text index for sc_cat_item table. This can be done by going to Catalog Item collection record, and clicking on Generate Text Index related link. Once the text indexing is finished, the results with 'use_desktop_picture' in 'mobile_picture_type' will no longer be returned.
Below is the link to documentation for more information on process of regenerate text index for a table :