This is the 10983rd most frequent Spanish word.
disipar
To disperse, dissipate, or clear away.
Here, 'disipar' is used in a literal sense, meaning 'to disperse' or 'to make disappear' something physical, such as clouds.
El fuerte viento ayudó a disipar las nubes.
The strong wind helped dissipate the clouds.
In this instance, 'disipar' is employed figuratively to indicate 'clearing up' or resolving something abstract, like doubts or confusion.
Tu explicación sirvió para disipar mis dudas.
Your explanation served to dissipate my doubts.
Here, 'disipar' is reflexive, denoting the process of an emotion or feeling gradually disappearing on its own.