Inseam This is the seam that runs inside the leg of pants from the crotch to the hem. Mens and womens pants are often labeled with an inseam length for sizing purposes.
Interfacing Interfacing is a type of material that is used on the wrong side of fabric or between layers to provide support and strength to the main fabric. Some common applications of interfacing include underneath where buttonholes will be sewn and inside shirt collars and waistbands to keep them upright and stiff. Interfacing is available in different weights and types depending on the intended use. There are knit interfacings for use on knit fabrics as well as woven. There are also fusible and non-fusible varieties. Fusible interfacings have a heat-activated adhesive on one side and they are applied using heat, usually from a household iron. Non-fusible interfacings must be sewn into the garment. Whether to use a fusible or non-fusible is generally personal preference. Try both and see what you prefer. I keep both on hand and decide which to use based on the fabric I am using and the item I am constructing.
Iron This is an electrical device that is used for pressing fabric flat or to remove creases. Most irons are available with a steam option which is helpful, especially when working with cotton fabrics. I consider an iron to be a staple in the sewing process and when I begin sewing, the first thing I do is to set up my ironing board.
Inverted pleat This type of pleat is created by making two pleats that face each other and meet in the middle on the front side. The technique is the same as a box pleat.
To make an inverted pleat, place a pin at the center of the pleat where the two pleats will meet from the sides and fold the fabric right sides together. Determine how wide you want the back side of the pleat to be. Measure out from the middle fold how deep you want the pleat to be and pin through both layers of fabric. For example, if you want the pleat to be an inch wide, measure one inch from the center and pin (the smaller folded areas will be half the size). To make the pleat, press on the center fold until the fabric begins to bow out on the edges making two folds. Bring the pin in the center fold toward the other pin so that they meet up while opening the fabric on the right side to create the pleats. Flatten the pleat and press gently with an iron to set it. Baste the pleat down near the top. It sounds complicated, but once you try it, it will make sense. To make a box pleat, fold the fabric wrong side together at the beginning.
Jean jumper This is a small plastic device that makes it easier to sew over thick seams on denim (or other heavy fabrics) by supporting the presser foot while it goes up and over the seam. If you try to sew through a thick seam without it, you may suffer from skipped or uneven stitches so it is a handy tool to keep in your sewing box. So you can see what it looks like, at the bottom of the page, I have linked to the Jean-A-Ma-Jig that is available at JoAnn.com.
Kimono sleeve This is a style of sleeve that is cut together with the body of the garment and is usually square cut. It fits very differently from a set-in sleeve.
Knit fabric Knit fabric is made using a system of interlocking loops made from a single continuous yarn. Knit fabric has more stretch than woven.
Knife pleats These are also called straight pleats. Knife/straight pleats are folds that all face the same direction.