There is no direct translation to the English word "ponder" in Spanish. Some close synonyms are listed below:
Sopesar - Weigh the merits (this is the closest to ponder)
Meditar - Meditate
Refleccionar (reflexionar) - Reflect
Pensar - Think
Considerar - consider
There is no spanish word spelled ponder. There is a Spanish word "poner" which means "to put" or "to place" in English.