The four groups of Buddhist disciples. See 四輩. 

The four classes, e. g. srota-āpanna, sakrdāgāmin, anāgāmin, and arhat. v. 四道.

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

catuṣ-prakāra, catvāro nikāyāḥ.

佛教漢梵大辭典, 平川彰 Buddhist Chinese-Sanskrit Dictionary, Akira Hirakawa

p 623

四部 (sì bù) 　( “the four groups of Buddhists, i.e. monks, nuns, laymen, and laywomen” ) Cf. 四輩(sì bèi) etc. ;

{《漢語大詞典》3.587a(陳代)} ; {《大漢和辞典》3.38c(梁書)} ;

Dharmarakṣa: {95c3} 闡弘誼趣，解暢槃結；應答四部，不以厭惓，…………捨除如來、菩薩、大士，辯才、質疑，未曾有如滿願子者(p)

{K.200.4} catur~ parṣad~

Kumārajīva: {L.27b26} 四衆

Dharmarakṣa: {100b20} 佛皆授斯四部之決：“當得無上正眞道意。”(p)

{K.224.7} do.

Kumārajīva: {not found at L.30c6}

Dharmarakṣa: {101c23} 如來滅度之後，若有菩薩及大士等欲以是經爲四部説，著如來衣，坐於世尊師子之座(v)

{K.234.4} do.

Kumārajīva: {L.31c22} 四衆

Dharmarakṣa: {122c1}

{K.375.3-}

Kumārajīva: {not found at L.50b25}

Dharmarakṣa: {122c28}

{K.378.5} bhikṣu~ vā bhikṣuṇī~ vôpāsaka~ vôpāsikā~ vā

Kumārajīva: {L.50c22} 四衆

Dharmarakṣa: {123a1}

{K.378.8} do.

Kumārajīva: {L.50c23} do. 

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