at all = اَلْبَتّةَ

The verb بَتَّ (batta) means to cut off, sever something. The verbal noun from this is بَتٌّ . In negative sentences, this verbal noun is used with an الْ attached to it, and also a ة (which is being used here, as in many other Arabic words, for emphasis, e.g. عَلاَّم is someone very learned, but علاَّمَة , with a ة attached, is someone very very learned, or a great scholar), in the accusative case, i.e. اَلْبَتّةَ (al-battah), to emphasise the negation, e.g. مَا كَلَّمْتُهُ الْبَتَّةَ I didn’t speak to him at all, as if you’re cutting off the possibility that you might have spoken to him.