► 副詞突然 [とつぜん]
meaning: sudden rank: 1☆ 突然
爆発音がした ⇨ Suddenly I heard an explosion
☆ 突然雨が
降り出した ⇨ Suddenly it started raining
突然 [とつぜん]
meaning: unexpected rank: 1☆ それは
全く突然の
出来事だった ⇨ That was a completely unexpected, out-of-the blue, incident
(☛ Sudden and unexpected)