1. superlative form of mournful; most expressive of or characterized by deep sorrow, grief, or lamentation
Usage: superlative degree; literary or formal register

Examples

• The mournfullest cry echoed through the cemetery at the funeral.
• Her mournfullest expression revealed the depth of her grief.
• The mournfullest notes of the violin seemed to capture everyone's sorrow.
• In his mournfullest voice, he recited the eulogy.
• The mournfullest day of the year was when they remembered those lost in the tragedy.