أَسْطُرْلَابٌ or أُسْطُرْلَابٌ, [accord. to different copies of the Ḳ,] and with ص in the place of س, [from the Greek ἀστρολαβόν, An astrolabe: a word of which F gives the following fanciful derivation:] لاب was a man who traced some lines, and founded upon them calculations; whence أَسْطُرُلَابٍ [the lines of Láb], from which was formed the compound word اسطرلاب, and اصطرلاب, the س being changed into ص because of the ط following. (Ḳ in art. لوب.) It is either an arabicized or a post-classical word: accord. to the Niháyet el-Adab, the names of all the instruments by which time is known, whether by means of calculation or water or sand, are foreign to the Arabic language. (MF.)