Yeah, I made that genitive up, but only to describe a real phenomenon in Latin! Some adjectives of likeness, nearness, and belonging that normally take the dative will occasionally take a possessive genitive. This transition is especially common where the adjective approaches the force of a noun.
Fuit hōc quondam proprium populī Rōmānī: this was once peculiar to the Roman people. (~a peculiar trait of)
Fuit semper amīcus Cicerōnis: he was always friendly with Cicero. (~a friend of)
Adeō patris similis es: you’re just like your master. (~a chip off the old block)
Here’s the full list of adjectives that perform this function—
aequālis, aequāle: of the same age (~a contemporary of)
affīnis, affīne: related to by marriage (~kinsman of)
aliēnus, -a, -um: belonging to another (~a stranger to)
cōgnātus, -a, -um: fellow-born (~kinsman of)
commūnis, commūne: common to (~kinsman of)
cōnsanguineus, -a, -um: sharing a bloodline (~kinsman of)
contrārius, -a, -um: opposite (~the opposite of)
dispār: unlike (dispar suī, in philosophical diction)
familiāris, familiāre: of close relation (~intimate of)
fīnitimus, -a, -um: adjoining (~neighbor of)
inimīcus, -a, -um: hostile to (~enemy of)
necessārius, -a, -um: connected with (~component of)
pār: equal to (~a match)
pecūliāris, pecūliāre: personal (~peculiar trait of)
propinquus, -a, -um: neighboring (~neighbor of)
proprius, -a, -um: personal (~peculiar trait of)
sacer, sacra, sacrum: holy (~holy with respect to some deity)
similis, simile: alike to (~spitting image of)
superstes: surviving (~survivor of)
vīcīnus, -a, -um: neighboring (~neighbor of)
Note that this genitive construction is actually more common for proprius, -a, -um than the dative construction.
Similis with the genitive is especially common with personal pronouns (meī, tuī, suī) and within the fixed phrase vērī similis (probable).
interdīco, interdīcere, interdīxī, interdīctus: forbid Interdīco (forbid) gets a note of it’s own in A&G because it’s case constructions have varied over time.
Earlier writers present interdīco +dative Person & ablative Thing Forbidden
Later writers use interdīco + dative Person & accusative Thing Forbidden
They forbade him fire and water: aquā et īgnī eō interdīxērunt.*
Shall we forbid the women from wearing purple: fēminīs purpurae ūsū interdīcēmus?
He forbade the actors from appearing on the stage: histriōnibus scaenam accedere interdīxit.
*This was the standard formally for expressing ‘he is banished’
Also, I discovered during the construction of this post that ‘forbid’ is never the past tense of the English ‘forbid.’ It is usually ‘forbade’ and rarely ‘forbad.’ I hope I wasn’t the only person making this mistake… for 21 years…