slander, gossip, rumors
諑 centers on harmful speech: spreading false or damaging talk about someone, including slander, gossip, and rumors.
諑 combines 言 (speech) with 豖, which likely contributes the sound and may relate to piercing or striking, suggesting sharp or harmful words.
Words (言) that strike like a pointed tool (豖) are slander and gossip. Picture sharp speech piercing someone's reputation.
For タク, imagine a tack being used to pin up a nasty rumor: tack -> タク, and the sharp words spread like a pinned note.