1. The initial group or batch of people, things, or events in a series
The first wave of immigrants arrived in the early 1900s.
A primeira onda de imigrantes chegou no início de 1900.
2. The opening phase or initial assault in a military operation
The first wave of troops stormed the beach at dawn.
A primeira onda de tropas invadiu a praia ao amanhecer.
3. The initial stage of a pandemic, social movement, or trend
The first wave of COVID-19 cases overwhelmed hospitals.
A primeira onda de casos de COVID-19 sobrecarregou os hospitais.