Meanings
From Middle English leten sliden (“to disregard, put aside, let pass, neglect”), equivalent to let + slide.
How to pronounce "let slide":
To let go, allow, release, pass over without action.
Example: "The police officer let the ticket slide when she found her brother-in-law's car illegally parked."
Example: "The administrator let the minor infraction slide with only a disapproving look."
To pass out of one's thought as not being of any consequence.
To tolerate a violation of a norm from.
Example: "The judge let me slide on the speeding, but not on a $200 seat-belt violation."
To allow the condition of something to deteriorate due to negligence or apathy.
Example: "He let the farm slide after inheriting it from his father."
Used other than figuratively or idiomatically: see let, slide.