This is the 15078th most frequent German word.
spendenden
"Spendenden" means "donating" or "giving" in English.
In this sentence, 'spendenden' modifies 'Mitgliedern' and denotes individuals who donate, used as an adjective.
Er dankte den spendenden Mitgliedern für ihre Großzügigkeit.
He thanked the donating members for their generosity.
Here, 'spendende' describes an entity 'Die Sonne' which gives or provides the quality of energy, used adjectivally.
Die Sonne ist eine Energie spendende Kraft.
The sun is a force that provides energy.
Here, 'spendenden' is associated with 'Taten' and provides additional information about the nature of these deeds, that they are acts of giving.