feeble

Feeble describes someone who is weak or a half-hearted attempt or something that is faint or unconvincing. (adjective)

An example of feeble is an old person who is sick and who can't get out of bed on her own.
An example of feeble is using the excuse that your car broke down when you are late even though the person who you are meeting knows your car is fine.
An example of feeble is trying for only one second to solve a problem before giving up.

See feeble in Webster's New World College Dictionary