Definition of tildes:
(n) :
A symbol ⟨~⟩, with various names and uses, also known as swung dash or wave dash. In the computer industry, various other names may be used, such as squiggle and twiddle.
(n) :
The character encoded as decimal 126 in the 1967 ASCII character set, and later in the 1992 Unicode character set.
(n) :
A diacritical mark ⟨˜⟩ placed above a letter to modify its pronunciation.
(n) :
In Spanish, ⟨ñ⟩ is a palatalized ⟨n⟩, for example in ⟨cañón⟩.
(n) :
In Portuguese, ⟨ã⟩ and ⟨õ⟩ are nasalized vowels, for example in ⟨canção⟩.
(n) :
May be used to represent approximation, in English prose and in mathematics. For example, “My dog weighs ~30 pounds.”