Mount Adams is a stratovolcano located in the Cascade Range of Washington, United States. Standing at 12,276 ft (3,742 m) feet, it is the second-highest mountain in Washington and a prominent feature within the Cascade Volcanic Arc, which formed as a result of the subduction of the Juan de Fuca Plate beneath the North American Plate. Adams is near two more-frequently erupting neighbors, Mount St Helens and Mount Rainier. It has twelve named glaciers descending its slopes.

Geologically, Mount Adams first formed in the Pleistocene. Its construction involved multiple eruptive phases, the first around 500,000 years ago, followed by the development of the modern cone around 10,000 years ago. The last known lava flow was approximately 1,000 years ago. The volcano has the potential for future hazards, including lahars, pyroclastic flows, and ashfall. Its deeply eroded flanks drain into major regional rivers like the Cispus, Klickitat and Lewis Rivers.

The mountain is home to diverse ecological zones, ranging from dense lower-elevation forests dominated by Douglas fir and western hemlock on its western slopes to drier ponderosa pine forests on its eastern slopes. These ecosystems support a rich array of flora and fauna, including large mammals like Roosevelt elk and black-tailed deer, as well as a variety of bird species and abundant wildflowers in the summer months.

The Yakama Nation, who reside on the eastern slopes, incorporated the mountain into their legends before the Europeans arrived. European-American explorers first documented the peak in the early to mid-19th century. The mountain was officially named after President John Adams in 1853, although the assignment of the name to the peak was due to mapmaker confusion. The first recorded ascent was made in 1854. Today, a significant portion of Adams is designated as the Mount Adams Wilderness.

Mount Adams is a popular destination for outdoor enthusiasts, offering a range of activities. Mountaineering is prominent, with the non-technical South Spur being the easiest climbing route to the summit. Hiking, backpacking, and camping are popular throughout the warmer months. The Pacific Crest Trail traverses the western flank of the mountain. In winter, visitors enjoy cross-country skiing and snowmobiling.

There are several names for the mountain in the various Indigenous languages in its vicinity. In the Sahaptin language to the east, it is called Pátu. The word pátu can refer to any snow-covered mountain, but the "main" pátu is Mount Adams. This name has been anglicized variously as Paton, Pahto, Pahtoo, Pahtoe, and Pat-to. It is also nicknamed X̱wayamá in the Yakama dialect of Sahaptin. This name means "golden eagle" and references the shape of a golden eagle appearing in the snowcap.

In the Cowlitz language to the northwest, it is called cʼilíləɬ. Additionally, there is the name patúʔ, which is loaned from the Sahaptin name.

To the south is the Upper Chinook language. An early-20th century mountaineer, William Denison Lyman recorded a Wasco-dialect name for the mountain, "Kakon," which he stated can refer to any high mountain.^{[non-primary source needed]}