Wavelength
Wavelength is how far an electro magnetic wave travels during one cycle.  When discussing DVR, the term refers to the color of light, which every color having a different wavelength.

Wavelet
This type of image compression is mainly used for single images and not video streams.  Because it’s superior to JPEG compression, it is however used in some video surveillance codecs, though there isn’t a universally adopted standard for usage of this codec.

WDM (Wavelength Division Multiplexing)
This economical procedure enables data from different sources to be simultaneously transmitted over the same fiber optic link.  It achieves this by assigning a unique wavelength to each data channel, resulting in many possible wavelengths traveling across one link, which allows one fiber link to do the same work as two or more.

Webcam
Webcams are cameras that connect to the Internet, either via PC or directly, and that allow remote user access.  An IP camera is a popular webcam for video surveillance that does not need a PC connection.

White balance
CCD security cameras feature this adjustment to compensate for ambient light color.  Since there’s a color difference between standard light bulb light and sunlight, white balance adjusts to ensure a more realistic picture.  This feature may be set by manual adjustment, or it may have preset settings for the most common situations.

Wide angle lens
This lens enables a wide view of the scene, with a magnification ratio less than 1. 

Wireless
The wireless transmission of video signals can be carried out over both short and long ranges, with 2.4 to 5 GHz devices for short distances and high-power line dedicated site solutions for several miles or more.