インク
いんく
inku
= ink (for pens, printers, stamps)
Inku is a straightforward katakana borrowing of the English word “ink,” and it behaves exactly how you’d expect for pens, printers, and stamps. But Japanese doesn’t stretch it to cover everything ink-related: traditional calligraphy uses its own native word, sumi, so reaching for inku in a shodo class instantly marks you as a beginner.
Inku refers to modern, manufactured ink — the cartridge inside a fountain pen (万年筆), the oily fill of a ballpoint, or the liquid in a home printer (プリンターのインク). It’s a purely practical, everyday word with no special register, as at home in a stationery shop as on an office supply order form. Where it does not apply is traditional Japanese calligraphy (書道, shodo) or ink-wash painting (水墨画): that solid black stick or liquid, ground on an inkstone, is called sumi, a native word carrying centuries of cultural weight. Mixing the two up isn’t just a small vocabulary slip — it signals that you don’t realize calligraphy ink is a completely different material tradition from printer cartridges.
Pronounce it crisply in three moras, i-n-ku, with a light nasal n and no extra vowel sound tacked onto the final ku. Use inku for anything manufactured — pens, markers, printers, stamp pads — and save sumi strictly for calligraphy and ink-wash art. One handy set phrase to know: inku-gire (インク切れ) means “out of ink,” the exact phrase printed on printer error messages and cartridge boxes when a pen or printer runs dry.
Everyday use
プリンターのインクが切れたので、コンビニでコピーしてきた。
Purintā no inku ga kireta node, konbini de kopī shite kita.
The printer ran out of ink, so I went and made copies at the convenience store instead.
Casual / Social Media
このボールペン、インクがにじんでノートが汚くなった…最悪。
Kono bōrupen, inku ga nijinde nōto ga kitanaku natta… saiaku.
This ballpoint’s ink smudged and turned my notebook into a mess… the worst.
Formal / Cultural context
店員に「万年筆用のインクはどこですか」と聞いたら、書道用の墨とは別の棚に案内された。
Ten’in ni “Mannenhitsu-yō no inku wa doko desu ka” to kiitara, shodō-yō no sumi to wa betsu no tana ni annai sareta.
I asked the clerk, “Where’s the ink for fountain pens?” and was led to a shelf entirely separate from the sumi used for calligraphy.
When Western-style writing instruments — fountain pens, then ballpoints — arrived in Japan in the late 19th and 20th centuries, they brought their liquid ink along with them, and the language simply borrowed the English word rather than repurposing an existing one. That choice makes sense: Japan already had a millennia-old ink tradition in sumi, ground from soot and animal glue on an inkstone (すずり, suzuri) for brush writing, so there was no need to stretch that word to cover a foreign product made with different materials for different tools. Inku and sumi ended up sitting side by side as two separate categories instead of one absorbing the other.
That split still shapes how the words get used today. Japan has an outsized, well-known stationery culture — brands like Pilot, Sailor, and Platinum produce fountain pens and bottled inku prized by enthusiasts worldwide, and hobbyist shops stock dozens of proprietary ink colors for pen collectors to sample. Sumi, meanwhile, stays tied almost exclusively to shodo classrooms, art supply stores, and cultural events, rarely surfacing in casual conversation outside that world. Knowing which word belongs to which world is a small but real marker of vocabulary fluency.