Words have a lexical meaning and a legislative meaning. The word Salaah means to perform specific actions in a specific manner [referred to as prayer] when we talk legislatively.
However, lexically it simply means to make du'a.
When a word has a legislatively meaning, you have a group of scholars who say that the word will always be understood according to the legislative meaning in the Nusuus [texts of the Qur’aan and Sunnah] unless there is evidence that it is being used according to its lexical meaning.
Then you have a group who believe that the word will always be understood according to its lexical meaning unless and until there is evidence that the word is being used in its legislative capacity.
To understand the affect this has when one tries to derive rulings from the texts consider the following hadiith:
al-Tawaaf around the Sacred House is al-Salaah
The group of scholars who hold that the word al-Salaah is to be understood in its lexical capacity until there is evidence to suggest otherwise, will take this word in its lexical meaning which means to make du'a. Hence, according to this group one does not have to have made Wuduu' when one performs al-Tawaaf as Wuduu is not necessary when one makes du'a.
The group of scholars who say that a word is understood in its legislative meaning until there is evidence to suggest that the word is being used in its lexical capacity will take the word al-Salaah to mean prayer. According to them, you will have to have performed Wuduu before you perform al-Tawaaf because Wuduu is necessary for prayer and al-Tawaaf is prayer.
al-'inaarah sharH kitaab al-'ishaarah