-енный

• IPA^(key): [ʲɪn(ː)ɨj]

• -ённый (-jónnyj) (when stressed)

-енный • (-ennyj)

1. used to form past passive participles from verbs in -ить (-itʹ) and -еть (-etʹ), which are frequently lexicalized into adjectives

   ‎просла́вить (proslávitʹ, “to celebrate”) + ‎-енный (-ennyj) → ‎просла́вленный (proslávlennyj, “celebrated”)

• As a means of forming past passive participles, the suffix as written occurs only unstressed; when stressed, it assumes the form -ённый (-jónnyj). Generally, this suffix occurs with accent-a verbs (stem-stressed verbs ending in unstressed -ить (-itʹ) and -еть (-etʹ)) and accent-c verbs (ending-stressed verbs in -и́ть (-ítʹ) and -е́ть (-étʹ), where the present and synthetic future tense, except for the first person singular, are stem-stressed, for example води́ть (vodítʹ) with present tense вожу́ (vožú), во́дишь (vódišʹ), во́дит (vódit), etc.). It does not normally occur with accent-b verbs (ending-stressed verbs where the entire present and synthetic future tense is ending-stressed, for example вини́ть (vinítʹ) with present tense виню́ (vinjú), вини́шь (viníšʹ), вини́т (vinít), etc.), which instead use -ённый (-jónnyj). However, there are exceptions in both directions, e.g. accent-c дели́ть (delítʹ) (present tense делю́ (deljú), де́лишь (délišʹ)) with past passive participle делённый (deljónnyj) and accent-b крои́ть (kroítʹ) (present tense крою́ (krojú), крои́шь (kroíšʹ)) with past passive participle кро́енный (krójennyj).
• This suffix triggers iotation (unlike the homophonous adjective-forming suffix below).

• -анный (-annyj)
• -янный (-jannyj)
• -нный (-nnyj)

• -тый (-tyj)

• -енный: IPA^(key): [ʲɪn(ː)ɨj]
• -е́нный: IPA^(key): [ˈʲenːɨj]

-енный or -е́нный • (-ennyj or -énnyj)

1. used to form adjectives from nouns, with the meaning "having the property of X"

   ‎простра́нство (prostránstvo, “space”) + ‎-енный (-ennyj) → ‎простра́нственный (prostránstvennyj, “spatial”)

   ‎целому́дрие (celomúdrije, “chastity”) + ‎-енный (-ennyj) → ‎целому́дренный (celomúdrennyj, “chaste”)

   ‎ма́лый (mályj, “small”) + ‎число́ (čisló, “number”) + ‎-енный (-ennyj) → ‎малочи́сленный (maločíslennyj, “scanty, few”)

2. used to form adjectives from other adjectives, with the colloquial meaning "very X"

   ‎высо́кий (vysókij, “high, tall”) + ‎-е́нный (-énnyj) → ‎высоче́нный (vysočénnyj, “very high, very tall (colloquial)”)

   ‎здоро́вый (zdoróvyj, “healthy; strong; big”) + ‎-е́нный (-énnyj) → ‎здорове́нный (zdorovénnyj, “very strong, very muscular; huge, enormous (colloquial)”)

• This suffix triggers the Slavic first palatalization of velars, but does not trigger iotation (unlike the homophonous past-participle-forming suffix above).
• In the colloquial meaning "very X", the suffix is normally stressed, while in the meaning "having the property of X" it is normally unstressed.