
A seam created by sewing fabric wrong sides together, trimming one of the seam allowances close to the seam, then turning the other seam allowance under and top stitching it over the prior trimmed seam allowance. This is often used for reinforcing seams on pajamas or to reduce bulk in a seam. It can be used as a decorative finish on any garment.
Found on
http://www.thesewingdictionary.com/

Used mainly in activewear, sportsware , this is a seam made by placing one edge inside a folded edge of fabric, then stitching the fold down with a top stitch.
Found on
https://sewguide.com/sewing-terms-glossary/

a seam on the face of a garment, as on the outside of the legs of blue jeans, made by overlapping or interlocking one seam allowance with the other and top-stitching them together onto the garment with two parallel rows of stitches.
Found on
https://www.infoplease.com/dictionary/flat-felled-seam
No exact match found.