The definition for accessible is "Easy to reach or to approach." Used in a sentence: The introduction to the complex novel was, thankfully, written in clear accessible language.

The definition for commemorate is "To mark by a ceremony." Used in a sentence: Each year, the Franklins commemorate their anniversary by visiting the site of their first date.

The definition for heinous is "Shockingly evil." Used in a sentence: Eduardo's heinous betrayal of Lydia shocked even Latasha, who knew his evil ways.

The definition for onset is "Beginning." Used in a sentence: Crocuses bloom at the onset of spring, sometimes even before the snow melts.

The definition for placebo is "An inactive substance used in medical testing." Used in a sentence: Tom, who had taken the placebo, found that his allergy symptoms did not go away.