1. talk louder, publicly express a strong opinion
speak out against injustice
To 'speak out' means to express your opinions or beliefs publically. If you 'speak out' against something you publically declare your opposition to something. If someone asks you to 'speak out', it might mean that they want you to speak louder or to speak with consideration for an audience. To 'speak up' can mean to increase the volume or loudness of your voice, you can ask someone to 'speak up' if you can't hear them. To 'speak up' can also mean to make your voice heard on an important issue or point. You can speak up in a meeting to voice your opinion for example. To 'speak up against' something is to make your opposing views heard.