1) Slip down 
• (v. i.) To pass down by inheritance; to lapse.
De·lapse' intransitive verb [ imperfect & past participle Delapsed ; present participle & verbal noun Delapsing .] [ Latin delapsus , past participle of delabi to fall down; de- + labi to fall or side.] To p...
delapse 1. To fall or to slide down. 2. To slip down; to descend, to sink.