What is a word for onus?

Could you please clarify for me what you mean by "a word for onus"? Are you asking for a synonym for the word "onus" or are you seeking a term that describes a similar concept to the burden or responsibility that the word "onus" often conveys? If it's the latter, then some possible phrases or words that might capture a similar idea could include "duty," "obligation," "responsibility," or "liability." However, it's important to note that these terms may not be exact synonyms and may have subtle differences in meaning depending on the context in which they are used.