Sentence:  We live our lives in three dimensions for our threescore and ten allotted years. Yet every branch of contemporary science, from statistics to cosmology, alludes to processes that operate on scales outside of human experience: the millisecond and the nanometer, the <WSD>eon</WSD> and the light-year. 
Meaning of the word marked with <WSD> tags:  A period of 1,000,000,000 years.