1. continuing for a long time; taking more time than expected or desired
2. having great length; very long in physical dimension

Examples

• The meeting turned into a lengthy discussion about budget cuts.
• After a lengthy delay, the flight finally departed.
• She wrote a lengthy letter explaining her decision.
• The lengthy process of applying for citizenship took two years.
• The lengthy corridor stretched the entire width of the building.
• His lengthy speech bored most of the audience.
• The lengthy novel took me three weeks to finish.