Really wouldn't consider either band to be Metal (at least, not anymore), but Within Temptation and Delain both have songs by that name.
Viens Mallika
Frozen - song - was created on 1998-02-23.
Not sure if this is what you're looking for, but an operatic solo is referred to as an aria.
O Mio Babbino caro" from Gianni Schicchi, by Puccini.
Frozen - Delain song - was created on 2007-01-08.
Ice is a non-metal. It is frozen water.
A hot frozen mess.
The song "Let It Go" from the movie Frozen is in the key of F minor.
An aria is an extended operatic solo.
It depends which language the phrase is in. An aria is usually an operatic song. Nos da means goodnight in Welsh. In Portuguese the phrase means 'in the song'.
A song from an Opera is known as an Aria - whether it is long or short, however, you can also have an arietta, which is a "little aria" which might also be what you are referring to.
Any operatic solo is called an aria.