【Tedium】 , 【boredom】 ,  【ennui】 ,  【doldrums】  are comparable when they denote a state of dissatisfaction and weariness.

【Tedium】 suggests a repression of energy for lack of a proper or adequate outlet, and dullness or lowness of spirits resulting from irksome inactivity or from the irksome monotony of one′s pursuits or surroundings.

【Boredom】  adds to  【tedium】 suggestions of listlessness, dreariness, and unrest resulting either from a lack of interest in one′s pursuits or surroundings or from the fact that they pall or fail to excite interest.

【Ennui】 stresses profound dissatisfaction, discontent, or weariness of spirit; usually it suggests physical depression, languor, or lassitude as well as 【boredom】 .

【Doldrums】 applies to a phase or period of depression that in persons may be marked by listlessness, despondency, and flagging energy or in more general applications (as to economic activity) may be marked by inactivity and dullness.