What are the best answers for “so lacking in interest as to cause mental weariness”?

boring, deadening, irksome, tiresome, wearisome.

How many letters does the top answer for “so lacking in interest as to cause mental weariness” have?

The most common answer is boring (6 letters).

5 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

boring 6 letters wn-def

the act of drilling a hole in the earth in the hope of producing petroleum

deadening 9 letters wn-def

the act of making something futile and useless (as by routine)

irksome 7 letters wn-def

so lacking in interest as to cause mental weariness

tiresome 8 letters wn-def

so lacking in interest as to cause mental weariness

wearisome 9 letters wn-def

so lacking in interest as to cause mental weariness