Too much focus on one's career may lead to one being uninteresting company. / Too much hard work and not enough leisure time can be unhealthy.

comparative form of dull: more dull

One who, or that which, dulls.

superlative form of dull: most dull

(archaic) third-person singular simple present indicative form of dull

plural of duller

present participle of dullen; Dulling.

Third-person singular simple present indicative form of dullen; dulls

simple past tense and past participle of dullen; dulled

(transitive, nonstandard) To make dull or duller; to dull. / (intransitive, nonstandard) To become dull or duller; to dull.