The phrase "boring of tooth" is often used to describe someone or something that is dull or uninteresting. To communicate this idea, there are several synonyms that can be used, such as tedious, monotonous, unstimulating, uninspiring, and drab. If you're looking for a word that emphasizes a lack of excitement or enthusiasm, you might choose "ho-hum," "meh," or "blah." Alternatively, you could choose a word that implies a sense of weariness or exhaustion, such as "tiring," "fatiguing," or "wearying." Ultimately, the synonym you choose will depend on the specific context and the degree of boredom you want to convey.