"expressing sorrow; oppressed with grief; doleful," early 15c., morneful, from mourn + -ful. Related: Mournfully; mournfulness.
Entries linking to mournful
mourn v.
Middle English mornen, from Old English murnan "to feel or express sorrow, grief, or regret; bemoan, long after," also "be anxious about, be careful" (class III strong verb; past tense mearn, past participle murnen), from Proto-Germanic *murnan "to remember sorrowfully" (source also of Old Saxon mornon, Old High German mornen, Gothic maurnan "to mourn," Old Norse morna "to pine away"), probably from suffixed form of PIE root *(s)mer- (1) "to remember." Or, if the Old Norse sense is the base one, from *mer- "to die, wither."
Specifically, "to lament the death of" from c. 1300. Meaning "display the conventional appearance of grieving for a period following the death of someone" is from 1520s. Related: Mourned; mourning.
-ful
word-forming element attached to nouns (and in modern English to verb stems) and meaning "full of, having, characterized by," also "amount or volume contained" (handful, bellyful); from Old English -full, -ful, which is full (adj.) become a suffix by being coalesced with a preceding noun, but originally a separate word. Cognate with German -voll, Old Norse -fullr, Danish -fuld. Most English -ful adjectives at one time or another had both passive ("full of x") and active ("causing x; full of occasion for x") senses.
It is rare in Old English and Middle English, where full was much more commonly attached at the head of a word (for example Old English fulbrecan "to violate," fulslean "to kill outright," fulripod "mature;" Middle English had ful-comen "attain (a state), realize (a truth)," ful-lasting "durability," ful-thriven "complete, perfect," etc.).