惘然的英文：
dejected; disappointed

参考例句：

He looked about for her everywhere, feeling deeply frustrated at her disappearance.
他到处找她，对她的失踪感到十分惘然。

dejected是什么意思：
v. 使…沮丧
adj. 沮丧的

To lower in spirits;deject.
使沮丧，使灰心沮丧，情绪低落；使气馁

Such news dejects me.
这种消息令我沮丧。

It will deject your spirits.
它会令你们情绪低落。

Affected or marked by low spirits;dejected.
气馁的，垂头丧气的由低落的情绪影响或有此特征的；沮丧的

A man used to vicissitudes is not easily dejected. —— Samuel Johnson
饱经沧桑的人，不易沮丧。——约翰逊

disappointed是什么意思：
adj. 失望的；沮丧的

The act of disappointing.
使人失望的行为

The poorness of the play disappointed the audience.
这出剧的拙劣令观众失望了。

This disappointed his plans.
这件事使他的计划落空了。

The trip was insipid and disappointing.
这次旅游平淡无奇，令人失望。

Once again he was disappointed in love.
他又一次失恋了。