Meditation is the ability to still the mind into a state of quietness without our thoughts running helter skelter. It is the state of mind where all thoughts are focussed on the Paramathma and his Vibhutis (or attributes).  It is a state in which we dispel our memory of the plusses and minuses of our lives, where we do not dwell on desires, where we do not think ill of others, where we do not bear any grudges, and one in which we focus only on the eternal.

It is a state in which we lose or minimize awareness of the self. It is a state where the mind does not project itself or attach itself to worldly objects or other people. 

The mind works by dividing the perceived world into opposites.  The world of oppsites always results in a conflict that keeps the mind in turmoil during its wakeful state and a lot times, during its sleep state as well.   It also constantly seeks to attach itself to objects and people, becuase otherwise it goes into a vacuum and has nothing to hold on to. So it develops illusory likes and dislikes and constantly tries to project itself and attract others to interact with itself, so that it can be assured of its own self image.  This is why people like to be praised. This is an assurance for the mind that all is well within itself. This assurance is sought all the time and becomes a preoccupation to seek more and more during its entire conscious existence. 

Meditation is a state of complete detachment of the mind from the objects of the world. This may not be a state that can be held for too long - No worries, no concerns, no ambitions, no attachments, no constant contemplation of the self. In other words a conscious elimination of all the factors that plunge the mind into alternate states of misery and (false sense of) happiness.  

It can be gained only by practice of  contemplation of the Paramathma. To hold the mind on the Paramathma takes a lot of conviction and practice, simply because we think that we do not see him with our sense perception capabilities.