Defn: Inflammation of the tissues surrounding the bladder.

PERIDERM
Per"i*derm, n.

1. (Bot.)

Defn: The outer layer of bark.

2. (Zoöl.)

Defn: The hard outer covering of hydroids and other marine animals; the perisarc.

PERIDIASTOLE
Per`i*di*as"to*le, n. (Physiol.)

Defn: The almost inappreciable time which elapses between the systole and the diastole of the heart.

PERIDIUM
Pe*rid"i*um, n.; pl. Peridia. Etym: [NL., fr. Gr. (Bot.)

Defn: The envelope or coat of certain fungi, such as the puffballs and earthstars.