Answer:
Jejune(adj) : {dull, uninterested, insipid}; {immature, childish}; {non- nourishing, non-nutritional}
Sentences:-
1) Students are always jejune in Prof. Sharma's class [dull]
2) Since you are an IT professional, you should have handled the situation sagaciously rather than acting in a jejune manner [immature]
3) Being at onsite, I am having jejune diet and missing mother made cuisines [non-nourishing]