English or Japanese → Tokipona
Toki pona → English & Japanese
pi 之

    sep of, belonging to

    → pi orders a string of modifiers that could be interpreted in more than one way. 

        moku tomo sona - ?smartly home prepared meal
        moku pi tomo sona - school lunch (pi separates the compound tomo sona ‘school’)

        tomo telo nasa - ?the crazy toilet (tomo telo as a compound reads as ‘toilet)
        tomo pi telo nasa - a bar (pi separates telo nasa, ‘alcoholic drinks’). 

    → Other examples

        jan pi ma tomo - person of the city, a city-dweller
        kulupu pi toki pona - group of Toki Pona, the Toki Pona community
        nasin pi toki pona - ways of Toki Pona, the ideology behind Toki Pona
        jan lawa pi jan utala - leader of soldiers, a commander or general
        jan lawa pi tomo tawa kon - leader of airplanes, a pilot

        jan pi pona lukin - person of visual goodness, an attractive person
        jan pi ike lukin - person of visual badness, an ugly person
    → the personal pronoun mi, sina, ona, function also as possessive pronouns when placed after a noun. That doesn’t work for names. Using pi can clarify things here also. 

        kili mi - my fruit
        kili jan Susan - ?Susan fruit
        kili pi jan Susan - Susan’s fruit

    → More examples

        ma ona - her country
        ma pi jan Keli - Keli’s country
        len jan - somebody’s clothes
        len pi jan Lisa - Lisa’s clothes

    → Using pi with the plural pronouns like mi mute ‘we’ and ona mute ‘they’ 

        nimi pi mi mute - our names
        tomo pi ona mute - their houses 

        NB according to wikibooks.org, pi is required with plural pronouns 
    → Special usage of pi to express the opposite of some words
        jan wawa - a strong person
        jan pi wawa ala - a person of no strength; a weak person
        NB wikibooks.org suggests that pi can make a big difference: jan wawa ala ‘no strong person; no strong people’ versus jan pi wawa ala ‘person of no strength’ .

    → You can use pi to separate compounds to express ‘about; with regard to’

        mi toki pi jan ike - I talk(ed) about bad people
        compare: mi toki jan ike - ?I talk(ed) humanly evil (or something like that)
    NB wikibooks.org claims that one should only use pi in instances where it usefully separates compound words. wikibooks.org disapproves of mi toki pi jan (I talked about people) because mi toki jan would already be clear enough. However, apparently quite a few Toki pona speakers seem to use pi like that. 

    → You can use pi to express possession more explicitly: pi mi ‘mine’, pi sina ‘yours’, etc. 

        kili ni li pi mi - this fruit is mine
        tomo ni li pi jan Tom - that house is Tom’s
        ilo ni li pi sina - this tool is yours
        toki ni li pi mi mute - this language is ours

    → Possible errors using pi

    Simple compounds like jan lawa ‘leader’ or jan ma ‘a countryman’ don’t require pi. The author of wikibooks.org claims that pi should only be used in case a string of modifiers needs clarification. 
   A more obvious error is using pi instead of tan (in the meaning of ‘from’).  
        mi kama tan ma America- I come from America

pi ピ 之 〔分離符〕 名詞の直前に位置し、名詞句を仲介する。 ~の、~に属する。 moku pi tomo sona 「学校の給食」 moku tomo sona 「賢い家庭料理」