immediately is an adverb that means without any delay or right away.
Common usage examples:
1. "Please call me immediately when you arrive."
2. "The fire alarm sounded and everyone left immediately."
3. "I knew immediately that something was wrong."
Synonyms: right away, at once, instantly, promptly, without delay
immediately这词儿啊，就是"立马、马上、赶紧"的意思，一点儿都不带耽搁的那种。
咱们日常用得可多了，给您举几个例子：
1. "到了赶紧给我打电话啊"（Please call me immediately when you arrive）
2. "火警一响，大家伙儿立马就撤了"（The fire alarm sounded and everyone left immediately）
3. "我一眼就看出不对劲儿"（I knew immediately that something was wrong）
同义词整几个：right away（马上）、at once（立刻）、instantly（瞬间）、promptly（及时）、without delay（不耽搁）
小贴士：商务场合用这词儿显得倍儿专业，比如"请立即处理"（Please handle this immediately），比说"快点弄"可讲究多了。