несериозен

Adjective

 * 1) not serious
 * 2) frivolous, light, flighty, flippant, flip
 * 3) unimportant, insignificant
 * 4) flaky, flimsy, unreliable
 * 1) unimportant, insignificant
 * 2) flaky, flimsy, unreliable
 * 1) flaky, flimsy, unreliable
 * 1) flaky, flimsy, unreliable

Adjective

 * 1) not serious, flighty, frivolous, flippant
 * 2) unimportant, insignificant
 * 3) flaky, flimsy, unreliable