乃天台宗指法華以前，華嚴、方等、般若三時所說之圓教教理，以及在法華經（開三顯一）時所說之圓教教理而言。

佛光電子大辭典

p217

The two perfect doctrines, a term of the Tiantai School, called 今圓 (also 開顯圓 and 絶待圓) and 昔圓 (also 相待圓 ). 今圓 is the present really perfect 一實 doctrine arising from the Lotus Sūtra; 昔圓 is the older, or 相待 comparatively speaking perfect doctrine of the pre-Lotus teaching, that of the 藏, 通, and 別 schools; but the older was for limited salvation and not universal like the 今圓; these two are also termed 部圓 and 教圓 . The Huayan school has a division of the two perfections into 漸圓 gradual perfection and 頓圓 immediate perfection.

A Dictionary of Chinese Buddhist Terms, William Edward Soothill and Lewis Hodous

（名數）天台家之名數。一今圓，二昔圓。今圓又曰開顯圓，絕待圓，於今時之法華經開會藏通別之三教，顯揚一實絕待之圓教也。昔圓又曰相待圓，於昔時之諸經，藏通別三教相待而說之圓教也。故昔圓雖為自圓而不能使他為圓也。又有部圓教圓之二者。前四時部之圓，為相待，無開會他之用，法華部之圓，為絕待圓，有開會他之用，如此就部意判今昔二圓之麤妙，謂之部圓，今圓昔圓皆為圓教之體而無異，就教體今昔視為同一之圓教，謂之教圓。蓋依教圓，一切諸教不出八教也。依部圓，法華為超八醍醐也。【又】華嚴之清涼，分圓教為漸圓頓圓二者，為荊溪所破斥。【參見: 二頓】

丁福保《佛學大辭典》