weak

(adjective): Lacking in force (usually strength) or ability.
(adjective): Unable to sustain a great weight, pressure, or strain.
(adjective): Unable to withstand temptation, urgency, persuasion, etc.; easily impressed, moved, or overcome; accessible; vulnerable.
(adjective): Dilute, lacking in taste or potency.
(adjective): (grammar) Displaying a particular kind of inflection, including:
(adjective): That does not ionize completely into anions and cations in a solution.
(adjective): One of the four fundamental forces associated with nuclear decay.
(adjective): Bad or uncool.
(adjective): Having a narrow range of logical consequences; narrowly applicable. (Often contrasted with a strong statement which implies it.)
(adjective): Resulting from, or indicating, lack of judgment, discernment, or firmness; unwise; hence, foolish.
(adjective): Not having power to convince; not supported by force of reason or truth; unsustained.
(adjective): Lacking in vigour or expression.
(adjective): Not prevalent or effective, or not felt to be prevalent; not potent; feeble.
(adjective): Tending towards lower prices.
(adjective): Lacking contrast.