IPA: /əˈspɜːrsər/
KK: /æspɜrsər/
A person who makes damaging or false statements about someone or something, often to harm their reputation.
The politician was careful not to let any aspersers affect his campaign.
Asperser is derived from the Latin 'aspergere' (meaning to sprinkle or scatter), which is formed from 'ad-' (meaning to) and 'spargere' (meaning to scatter). The word 'asperser' refers to someone who sprinkles or scatters, often in a figurative sense, such as casting aspersions or doubts.
Think of someone 'scattering' ('spargere') doubts or criticisms 'to' ('ad-') others — that's why asperser means to cast doubt.