1
general::
1. Also, speak out. Talk loudly, so as to be heard, as in Speak up, child, I can't hear you, or He should speak out so that those in back can hear him. The first term dates from the early 1700s, the variant from the early 1500s. 2. Also, speak up for. Express one's opinion or one's support for someone or something. For example, When it comes to speaking up about the town's needs, you can rely on Mary, or I'm glad you spoke up for me in that meeting. [c. 1700]
American Heritage Idioms
2
general::
Phrase(s): speak up
1. Lit. to speak more loudly. • They can’t hear you in the back of the room. Please speak up. • What? Speak up, please. I’m hard of hearing. 2. Fig. to speak out (on something). • If you think that this is wrong, you must speak up and say so. • I’m too shy to speak up., Phrase(s): speak up (against someone or something)
to end one’s silence and speak negatively and publicly about someone or something. • She finally spoke up against her cruel boss. • We all felt like we had to speak up and denounce this tyrant.
McGrawhill's American Idioms And Phrasal Verbs