Why " LA" instead of "EL"??

Question

Why is it La Mano instead of it being El Mano? I thought because the word is masculine ( meaning ending with an O) it will begin with EL.

Hola,bienvenido al foro! - rac1, Jun 26, 2012

Answer 1

Those are mere exceptions to the masculine O ending, but you have to always keep that in mind if don't wanna sound funny, RADIO is another masculine-looking femenine word, although it is actually a contraction from radiodifusión.

Not to add mud to the water, but "radio" when applied to a radio set, as opposed to the process of transmission, is masculine. It is a contraction for "radiorecptor". "El radio" is the set, "la radio" is the transmission. - Noetol, Jun 26, 2012

Answer 2

Many times these exceptions are a contraction as diagonx says. Another exampe is la foto because it is a contraction of la fotografia. You just have to memorize these things.