The word "捐赠" is formed by combining the characters "捐" and "赠". "捐" uses the hand radical "扌" to indicate an action involving handing over, meaning to contribute or donate, while "赠" uses the shell radical "贝" to relate to valuables, meaning to give as a gift. Together, they create a compound word where both characters reinforce the idea of donating, specifically through the act of giving valuable items or money charitably.