The Beginner’s Guide to Window Terminology

Installer putting window into place

Sash, insulating glass, fenestration – what does it all mean? If you’re in the market for new windows and you come across these terms, you probably feel lost. Luckily, there’s hope for you. 

In this window terminology guide, you’ll learn the basic terms about the anatomy, installation, and experience of home windows. 

If you’re tired of hearing all these terms with no knowledge of their meaning, by the end of this blog post, you’ll be able to impress your window dealer with your familiarity with windows. 

Understanding Home Windows

Like most people, you’re probably not a window expert. Fortunately, we are! Which is why we’re imparting our knowledge to you. 

When you’re more educated about windows, you’re a more informed buyer. This will enable you to better distinguish what you’re looking for when shopping for windows, and help you make informed decisions. 

The Different Types of Windows

We’ll be going over more generic window terms in this article. However, if you’d like to learn more about what each different type of window is, you can read our previous article about the nine common home window types. Each window type is different and provides various aesthetic and functional benefits. So, without further ado, let’s get you educated on all things windows. 


Fenestration refers to any opening of a building, whether it be a door, window, or other open entry point. This is a big word used in the window and door industry. 


The window pane is simply the glass part of every window. Many windows have more than one pane for better insulation.


Window sashes describe the part of the window that holds the glass in place in the window frame. Sashes can be operable (movable) or inoperable, and stay in place. For example, double-hung windows are sometimes called ‘sash windows’ due to them having two operable sashes, allowing the top and bottom to open. 

Replacement Window

This term’s meaning is simply its title. A replacement window refers to a new window going into the opening of a previous existing window. How often you get your windows replaced depends on their quality, weather conditions, or if they’re damaged in any way. 


Glazing refers to a putty compound and its installation process that holds window glass in place, and seals the window from the outside. This term also applies to the number panes glass panes inside a window such as double pane or single pane. 

Insulated Glass

Insulated glass is when (2 or more) window panes are separated by space to reduce the transfer of heat. Oftentimes, the space between panes contain krypton gas to help with insulation. 

Krypton Gas

As mentioned above, krypton gas is used in between window panes to improve insulation. Krypton gas is odorless, colorless, and non-toxic. 

Window Grilles or Muntins

The terms ‘grilles’ and ‘muntins’ are often used interchangeably. However, historically speaking, there is a difference. Muntins were originally window pane dividers that divided the glass into smaller, patterned panes such as diamond or square. This is because smaller pieces of glass were easier to come across and cheaper to acquire. 


In modern day, window grilles (or muntins) are usually applied externally on one whole window pane. 


We hope this article gave you more insight and understanding into the world of windows. Now, you’re equipped to make informed buying decisions, helping you find the perfect windows for you.


If you’re looking for a reliable and trustworthy window dealer, Earthwise Windows is “The Wise Choice”. With over a dozen regional manufacturers around the United States, we’re able to offer something no other window manufacturer can: windows made specifically for your local climate. To find out more or get your quote, contact us today. 

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