第一宇宙速度

dì-yīyǔzhòusùdù
  1. (physics) first cosmic velocity
  2. first cosmic velocity

Wiktionary

Entry Composition

=1 第一 dìyī
  1. first
  2. most important; primary; foremost
=1 第一 dì-yī
  1. (literally, figuratively) first; 1st
  2. being the most important consideration; being essential, or a priority; coming first
  3. first; 1st
  4. firstly
  5. number one; #1; first (in a test, competition, etc.)
2 宇宙速度 yǔzhòusùdù escape velocity