We found one dictionary that defines the word first-order approximation:

General (1 matching dictionary)

1. First-order approximation: Wikipedia, the Free Encyclopedia

▸ Words similar to first-order approximation ▸ Usage examples for first-order approximation ▸ Idioms related to first-order approximation ▸ Wikipedia articles (New!) ▸ Words that often appear near first-order approximation ▸ Rhymes of first-order approximation ▸ Invented words related to first-order approximation