pledge
This word carries a heavy weight of formality and moral obligation. It is far more serious than a simple promise or a casual agreement, often implying a public declaration or a binding legal or spiritual commitment. It evokes a sense of honor and irreversibility, where breaking the word results in a significant loss of reputation or trust. In a modern social context, it is frequently used in the realm of fundraising and philanthropy. Here, it describes a commitment to donate a specific amount over time, shifting the focus from a spiritual oath to a financial obligation.
Countable when referring to a specific promise or a physical object used as collateral. Uncountable when referring to the general act of pledging or the state of being committed.