Originally Posted by ArnoldLayne
Your quite right the Word daha is use for the flatten depression where the ostrich lay's it's egg.
I will post the article:
Answered by the Scientific Research Committee - IslamToday.net
The word in question is the verb (dahâ) comes from the triliteral root d-h-w and it appears in the Qur’ân in relation to the Earth in the following verse: “And the Earth, after that, He spread out (dahâhâ).” [Sûrah al-Nâzi`ât: 30]
This word conveys one concept in the Arabic language: that of “spreading, leveling, flattening, and smoothing out”. Allah mentions this to us in the verse to show us something of his providence to us. He explains what he means by stretching the Earth out and smoothing it out in the following verses: “He brought forth from it its water and its pasturage, and He made the mountains firmly fixed.” [Sûrah al-Nâzi`ât : 31-32]
Therefore, Allah smoothed out the Earth for us by making it a stable and suitable place for habitation, providing its inhabitants with water, pasture, and keeping its mountains firmly-fixed.
With respect to this word’s association with eggs, it is as follows:
Due to the fact that the word conveys the meaning of “spreading, leveling, flattening, and smoothing out”, the Arabs named the place where an ostrich incubates and hatches its egg udhiyy. This is a hollow pit in the ground around 30 to 60 centimeters deep. The Arabic word for this shallow depression is derived from the triliteral root d-h-w. The reason for this is that the ostrich spreads out and flattens this area with its legs before laying its egg in it. The ostrich uses neither a nest nor a burrow for its eggs.
From this, we must understand that the word is not used for the egg itself but rather for the flattened depresion where the ostrich deposits its egg.
Whoever uses the word to refer to the egg or to the shape of the egg is being inexact in his linguistic usage. However, without doubt we can say that such an error does not detract from the person’s reputation or scholarship as a whole, and it does not warrant a harsh repremand.
In any case, verse 30 of Sûrah al-Nâzi`ât – that mentions the verb dahâ in reference to the Earth – is not discussing the shape of the Earth at all. It cannot be used as proof that the Earth is flat or round or egg-shaped. The verse is silent on the matter. And Allah knows best.
The exact shape of the Earth is best known from empirical observations, and not from seeking to deduce its exact shape from the Qur’ân.
The Earth is practically a perfect sphere, though due to its rotation, it bulges ever so slightly at the equator. Because of this, it is referred to as an oblate speroid. We must keep in mind that this equatorial bulge is extremely slight. The Earth’s equatorial diameter is only 43 kilometers greater than its polar diameter.
To get an idea of how insignificant this difference is, we can compare the spericity to the Earth to that of a billiard ball. A billiard ball must be very spherical. The tolerance allowed for a billiard ball is only 0.22%. (Tolerance, in engineering, refers to the permissible limit of variation in a dimension of a manufactured object.) The Earth, by comparison, has a tolerance of about one part in 584, or 0.17%. This means the Earth is more perfectly spherical than what is allowed for a billiard ball.
And Allah knows best.