a state in the northwestern region of the United States. Idaho is the 14th most expansive, the 39th most populous, and the 7th least densely populated of the 50 United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state.

Idaho is a mountainous state with an area larger than that of all of New England. It is landlocked, surrounded by the states of Washington, Oregon, Nevada, Utah, Wyoming, Montana and the Canadian province of British Columbia. However, the network of dams and locks on the Columbia River and Snake River make the city of Lewiston the farthest inland seaport on the Pacific coast of the contiguous United States.

Idaho's nickname is the "Gem State", because nearly every known type of gemstone has been found here.[5] In addition, Idaho is one of only two places in the world where star garnets can be found (the other is the Himalaya Mountains, in India).[6] Additionally Idaho is sometimes called the "Potato State" owing to its popular crop. The state motto is Esto Perpetua (Latin for "Let it be forever").

The exact origin of the name remains a mystery.[7] In the early 1860s, when the United States Congress was considering organizing a new territory in the Rocky Mountains, eccentric lobbyist George M. Willing suggested the name "Idaho," which he claimed was derived from a Shoshone language term meaning "the sun comes from the mountains" or "gem of the mountains". Willing later claimed that he had made up the name himself.[8][9] Congress ultimately decided to name the area Colorado Territory when it was created in February 1861. Thinking they would get a jump on the name, locals named a community in Colorado "Idaho Springs".

Lake Coeur d'Alene in North Idaho
However, the name "Idaho" did not go away. The same year Congress created Colorado Territory, a county called Idaho County was created in eastern Washington Territory. The county was named after a steamship named Idaho, which was launched on the Columbia River in 1860. It is unclear whether the steamship was named before or after Willing's claim was revealed. Regardless, a portion of Washington Territory, including Idaho County, was used to create Idaho Territory in 1863.

Despite this lack of evidence for the origin of the name, many textbooks well into the 20th century repeated as fact Willing's account that the name "Idaho" derived from the Shoshone term "ee-da-how".
The name "Idaho" may be derived from the Plains Apache word "ídaahę́" which means "enemy." The Comanches used this word to refer to the Idaho Territory.[10]

An excerpt from a 1956 Idaho history textbook:
"Idaho" is a Shoshoni Indian exclamation. The word consists of three parts. The first is "Ee", which in English conveys the idea of "coming down". The second is "dah" which is the Shoshoni stem or root for both "sun" and "mountain". The third syllable, "how", denotes the exclamation and stands for the same thing in Shoshoni that the exclamation mark (!) does in the English language. The Shoshoni word is "Ee-dah-how", and the Indian thought thus conveyed when translated into English means, "Behold! the sun coming down the mountain".[11]