as·tro·nau·tics \ˌ ̷ ̷ ̷ ̷ˈ ̷ ̷d.iks\noun plural but usually singular in construction Etymology: International Scientific Vocabulary astr- + -nautics (as in aeronautics) 1.: the science that treats of the construction and operation of vehicles designed to travel in interplanetary or interstellar space 2.: astrogation