bit by bit

Từ điển WordNet v3.1 - WordNet Dictionary

adverb

1. a little bit at a time
- the research structure has developed piecemeal
• Syn:
piecemeal, little by little, in stages
2. in a gradual manner
- the snake moved gradually toward its victim
• Syn:
gradually, step by step
• Derived from adjective:
gradual (for: gradually)