The four groups of Buddhist disciples: monks 比丘, nuns 比丘尼, laymen 優婆塞 and laywomen 優婆夷 (catur-parṣad).

The four grades: (1) bhiksu, bhiksunī, upāsaka, upāsikā, i. e. monks, nuns, male and female disciples, v. 四衆; (2) men, devas, nāgas, and ghosts 鬼.

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

四輩===﹝出翻譯名義﹞

〔一、比丘〕，梵語比丘，華言乞士。乞是乞求之名，士是清雅之稱。謂出家之人，上乞法以資慧命，下乞食以資色身，故名乞士。

〔二、比丘尼〕，梵語尼，華言女。佛初不度女人出家，成道之後，因姨母摩訶波闍波提懇求出家，佛乃度之，故名比丘尼。（梵語摩訶波闍波提，華言大愛道。）

〔三、優婆塞〕，梵語優婆塞，華言清淨士。謂雖在家，能持五戒，清淨自守；又云近事男，謂能持戒，可親近承事諸佛法，故名優婆塞。（五戒者，不殺、不盜、不邪婬、不妄語、不飲酒也。）

〔四、優婆夷〕，梵語優婆夷，華言清淨女，謂雖在家，亦能堅持五戒，清淨自守，故名優婆夷。

明，一如《三藏法數》字庫

出翻譯名義

四輩===（雜語）比丘、比丘尼、優婆塞、優婆夷之四眾也。又，人、天、龍、鬼之四眾也。藥師經曰：「四眾：苾芻、苾芻尼、鄔波素迦、鄔波斯迦。」盂蘭盆經曰：「時目連比丘四輩弟子歡喜奉行。」同圭峰疏曰：「四輩者，僧尼士女，或云人天龍鬼。」【參見: 四眾】

丁福保《佛學大辭典》

四輩 (sì bèi) 　( “the four groups of Buddhists, i.e. monks, nuns, laymen, and laywomen” ) Cf. 四輩弟子(sì bèi dì zǐ), 四部(sì bù), 四部弟子(sì bù dì zǐ), 四部之會(sì bù zhī huì), 四部之衆(sì bù zhī zhòng), 四部衆(sì bù zhòng), 四部衆會(sì bù zhòng huì) ;

{《漢語大詞典》3.598a(百喩經)} ; {《大漢和辞典》3.35d(盂蘭盆經)} ;

Dharmarakṣa: {64a14}

{K.9.1} parṣā~[O.pariṣā~] catur~

Kumārajīva: {L.2c13} 四部衆

Dharmarakṣa: {81b4} 然今最後，普令四輩比丘、比丘尼、清信士、清信女、天上、世間一切人民顯示本宜(p)

{K.110.10-}

Kumārajīva: {not found at L.17c9}

Dharmarakṣa: {92a20} 今我班宣四輩(p)

{≠ K.184.3} vo bhikṣavaḥ

Kumārajīva: {L.25b23} 諸比丘…汝

Dharmarakṣa: {102a2}

{K.234.12} catur~ parṣad~

Kumārajīva: {L.31c28} 四衆

Dharmarakṣa: {110b8}

{K.295.8} do.

Kumārajīva: {L.39c13} do.

Dharmarakṣa: {123a12}

{K.379.3} bhikṣu-bhikṣuṇy-upāsakôpāsikā~

Kumārajīva: {L.51a2} 比丘、比丘尼、優婆塞、優婆夷

Dharmarakṣa: {131a15}

{K.458.5-}

Kumārajīva: {not found at L.59c12} 

A Digital Edition of A Glossary of Dharmarakṣa translation of the Lotus Sutra by Seishi Karashima, 1998