Literature Reference: 于思于思，弃甲复来。——《诗经·小雅·采薇》 Yu Si, Yu Si, abandoning armor and returning again. Source from 'The Book of Songs: Xiao Ya: Cai Wei'.
于: Thus, it is.
思: Thought, intellect. In names, it often signifies quick thinking, sharp wit, and intelligence.
Meaning: Yu Si signifies deep contemplation, reflecting profound thought and wisdom.