The hieroglyph Akht (𓈌), meaning “horizon.” 

The hieroglyph Akht (𓈌), Gardiner Sign N27, depicts the sun positioned between two peaks, representing the place where the sun rises and sets on the horizon. In addition to being used in one of the names of the Great Sphinx, Horemakhet (“Horus on the Horizon”), it can also be used in words relating to tombs and the deceased ("horizon dwellers").

Source: Hieroglyphs created using JSesh.  Rosmorduc, Serge. (2014). JSesh Documentation. [online] Available at: https://jseshdoc.qenherkhopeshef.org [Accessed 12 Jun. 2014].