Sacagawea's name was since the beginning a matter of a great dispute. Correct spelling, pronunciation, and etymology of the woman's name is still matter of great debate. Widely accepted spelling of her name as it is used today comes from independently constructed form of two Hidatsa Indian words found in a dictionary titled Ethnography and Philology of the Hidatsa Indians as "tsa-ka-ka, noun; a bird," and "mia [wia, bia], noun; a woman. Although not closely following Hidatsa spelling, the pronunciation is quite similar and the Geographic Board acknowledged the name to be a Hidatsa word meaning "Bird Woman."
The name Sacajawea or Sacajewea, is said to be derived from Shoshone Saca-tzaw-meah, meaning "boat puller" or "boat launcher". This is the preferred spelling used by the Lemhi Shoshone people and probably that's what the Hidatsa captors merely reinterpreted existing Shoshone name in their own language, and pronounced it in their own dialect they heard a name that approximated "tsakaka" and "wia", and interpreted it as "bird woman", substituting the hard "g/k" pronunciation for the softer "tz/j" sound that did not exist in the Hidatsa language.
The usage of this spelling almost certainly originated from the use of the "j" spelling by Nicholas Biddle, who annotated the Lewis and Clark Expedition's journals for publication in 1814. This usage became more widespread with the publication of the 1902 novel, The Conquest: The True Story of Lewis and Clark, written by Eva Emery Dye.
Although the spelling Sacajawea was used until late 20th century, the use of it subsided and it is considered to be mistakenly pronounced. Due to the fact that it was long in usage, the "soft j" stayed in pronunciation to the majority of Americans. The term for 'boat' in Shoshoni is saiki, but the rest of the alleged compound would be incomprehensible to a native speaker of Shoshoni.
Sakakawea is the official spelling of her name according to the Three Affiliated Tribes, which include the Hidatsa, and is widely used throughout North Dakota.
It is interesting that Lewis and Clark had more than eight versions of her name in their journals. Clark used Sahkahgarwea, Sahcahgagwea, Sarcargahwea and Sahcahgahweah, while Lewis used Sahcahgahwea, Sahcahgarweah, Sahcargarweah and Sahcahgar Wea. What is certain, that both explorers wrote letter "G" in the third syllable and that is the way name was most frequently pronounced.
Lewis tried to give his rendition of the spelling of her name and also its meaning. His journal entry for May 20, 1805, reads: "a handsome river of about fifty yards in width discharged itself into the shell river... this stream we called Sah-ca-gah-we-ah or bird woman's River, after our interpreter the Snake woman."
However, Sacajawea or Sacagawea or Sakakwea, it is the same woman.