Answer to question: It appears that GOD Called it an "Ark" Genesis 6 (Amplified Bible) 8But Noah found grace (favor) in the eyes of the Lord.
9This is the history of the generations of Noah. Noah was a just and righteous man, blameless in his [evil] generation; Noah walked [in habitual fellowship] with God.
10And Noah became the father of three sons: Shem, Ham, and Japheth.
11The earth was depraved and putrid in God's sight, and the land was filled with violence (desecration, infringement, outrage, assault, and lust for power).
12And God looked upon the world and saw how degenerate, debased, and vicious it was, for all humanity had corrupted their way upon the earth and lost their true direction.
13God said to Noah, I intend to make an end of all flesh, for through men the land is filled with violence; and behold, I will [a]destroy them and the land.
14Make yourself an ark of gopher or cypress wood; make in it rooms (stalls, pens, coops, nests, cages, and compartments) and cover it inside and out with pitch (bitumen).
15And this is the way you are to make it: the length of the ark shall be 300 cubits, its breadth 50 cubits, and its height 30 cubits [that is, 450 ft. x 75 ft. x 45 ft.].
16You shall make a roof or [b]window [a place for light] for the ark and finish it to a cubit [at least 18 inches] above--and the [c]door of the ark you shall put in the side of it; and you shall make it with lower, second, and third stories.
17For behold, I, even I, will bring a flood of waters upon the earth to destroy and make putrid all flesh under the heavens in which are the breath and spirit of life; everything that is on the land shall die.
18But I will establish My covenant (promise, pledge) with you, and you shall come into the ark--you and your sons and your wife and your sons' wives with you.
19And of every living thing of all flesh [found on land], you shall bring two of every sort into the ark, to keep them alive with you; they shall be male and female.
20Of fowls and birds according to their kinds, of beasts according to their kinds, of every creeping thing of the ground according to its kind--two of every sort shall come in with you, that they may be kept alive.
21Also take with you every sort of food that is eaten, and you shall collect and store it up, and it shall serve as food for you and for them.
22Noah did this; he did all that God commanded him.
+++"Bible Dictionary
Ark
Noah's ark, a building of gopher-wood, and covered with pitch, 300 cubits long, 50 cubits broad, and 30 cubits high (Gen. 6:14-16); an oblong floating house of three stories, with a door in the side and a window in the roof. It was 100 years in building (Gen. 5:32; 7:6). It was intended to preserve certain persons and animals from the deluge which God was about to bring over the earth. It contained eight persons (Gen. 7:13; 2 Pet. 2:5), and of all "clean" animals seven pairs, and of "unclean" one pair, and of birds seven pairs of each sort (Gen. 7:2, 3). It was in the form of an oblong square, with flat bottom and sloping roof. Traditions of the Deluge, by which the race of man was swept from the earth, and of the ark of Noah have been found existing among all nations.".....