weak

Weak means not strong.

A synonym for weak in the context of physical strength is feeble. A person might also be considered weak as in cowardly or easily defeated.

Something that can easily break can be described as fragile or delicate.

When a sick or very tired person says they feel weak, it means they have no energy. A person who’s very ill and generally weak in this way might be described as frail.

When weak means lacking in force, effectiveness, or support, synonyms are ineffectual and poor, as in That’s a weak/poor excuse.

In the context of sounds, weak is used to mean faint, soft, and quiet. A weak sound might be one that’s indistinct, thin, or muffled.

A very informal slang term that can mean the same thing as weak is weak sauce.

To become weak is to weaken. A specific way of being weak is a weakness. Other terms for this are weak point, vulnerability, and soft spot. These terms often suggest a flaw that can allow someone or something to be defeated, attacked, exploited. An expression that means this is Achilles heel.