たいくつ退屈taikutsu
1.

A state characterized by a lack of engaging activities or stimulation, leading to an experience of time feeling prolonged and unproductive.

2.

A feeling of disinterest or dissatisfaction arising from monotony or a lack of excitement, often resulting in a diminished sense of enjoyment in one's surroundings or tasks.

3.

The sensation of weariness that can occur from repetitive or uninspiring experiences, causing a desire to escape or find something more fulfilling to occupy one's mind.

Example:

カクテルパーティーは退屈なときもある。

たいくつ退屈taikutsuしのぎshinogi
1.

Engaging in activities or distractions to alleviate feelings of monotony or tedium.

2.

Methods or pastimes employed to fill spare time and reduce a sense of ennui.

3.

The act of seeking entertainment or mental engagement in order to combat feelings of boredom.

Example:

この頃私は退屈しのぎに庭造りをしています。