The English word meditation comes from the Latin meditatio meaning ‘to ponder’ or ‘to ruminate.’ The Pali word usually translated as meditation is bhàvana and means ‘to develop,’ ‘to cultivate,’ or ‘to expand.’ Thus the word meditation is actually a poor description for the various techniques of psychological transformation taught by the Buddha.
In relation to thoughts, one could say that there are three approaches to meditation in Buddhism; (1) to utilize thoughts, (2) to still thoughts and (3) to observe thoughts.
Metta (loving-kindness) meditation would be an example of the first of these. The meditator deliberately thinks particular types of thoughts for the purpose of evoking certain emotions and behaviour. An example of the second of these types of meditation would be Mindfulness of Breathing, where the meditator focuses his or her attention on the breath thus slowing down and finally stopping the flow of thoughts. In Mindfulness meditation the mediator develops the ability to simply observe mental activity (thoughts, emotions, conceptualizing, etc) thus gradually becoming less influenced by them.
Tranquillity and Insight, A.Sole-Leris, 1992.