English definition of “lag behind (sb/sth)”
lag behind (sb/sth) — Phrasal Verb with lag
/læg/ verb (present participle lagging, past tense and past participle lagged)
MOVE SLOWLY › to move more slowly than someone or something else so that you are behind them
ACHIEVE LESS › to achieve less than someone or something else: Britain is lagging far behind the rest of Europe on this issue.