What is the definition of "Ayah" (verse) and "Surah" (chapter) linguistically and in Islamic law?

In the religious lexicon, a surah is a collection of Quranic verses, whose beginning and end are divinely ordained (tawqifan), and these surahs collectively form the Qur’an. A verse (ayah), on the other hand, is a word or a group of words from the Qur’an that make up a surah.

Scholars have differed regarding their etymology. It has been said that "surah" derives from concepts of clarification and elevation, or due to its honor, or because it is a portion of the Qur’an, or due to its completeness and perfection, or for its comprehensiveness and encompassing nature.

As for "ayah," it has been said to derive from the sign indicating the end of a discourse, or because it is a collection of letters from the Qur’an, or because it is a marvel that humans are incapable of producing anything similar to it.