Three consonants carry one idea: writing. Pour them into a verb mould and you get an action; pour them into a noun mould and you get the writer, the writing, or the written thing. None of the words below are memorized separately. They are the same three letters seen from different angles. Every word here is verified against pealim, niqqud included.
The verb across the binyanim (voices)
The same root runs through the verb system. Each binyan is a voice: it bends the one idea into active, passive, causative or reciprocal. Tap to hear.
Pa'al
לִכְתֹּבlichtov
simple active, the plain action to write
Nif'al
לְהִכָּתֵבlehikatev
passive / middle, it happens to the subject to be written
Pi'el
לְכַתֵּבlechatev
intensive / specialized active to address (a letter), to cc
Hif'il
לְהַכְתִּיבlehakhtiv
causative, make someone do it to dictate (cause to write)
Hitpa'el
לְהִתְכַּתֵּבlehitkatev
reflexive / reciprocal, to / on oneself to correspond, to write to one another
The passive partners pu'al and huf'al exist in the system but are not lexicalized for this root, so Hebrew uses nif'al for "to be written". That is normal: not every root fills all seven binyanim.
Words born from the root
Same root letters, different noun moulds (mishkalim). The mould tells you the function: who does it, the act of doing it, or the thing produced.
① The people: who writes
כַּתָּב
katav
reporter, journalist
קַטָּל
כַּתְבָן
katvan
graphomaniac, hack writer
קַטְלָן
② The act: the writing happening
כְּתִיבָה
ktiva
writing (the process), recording
קְטִילָה
הַכְתָּבָה
hakhtava
dictation
הַקְטָלָה
הִתְכַּתְּבוּת
hitkatvut
correspondence (by mail)
הִתְקַטְּלוּת
כִּיתּוּב
kituv
captioning, subtitling
קִיטּוּל
③ The written thing: the product
מִכְתָּב
mikhtav
a letter (mail)
מִקְטָל
כְּתָב
ktav
script, handwriting, a writing system
כָּתוּב
katuv
written (it is written)
קָטוּל
כַּתָּבָה
katava
a report, an article (journalism)
קַטָּלָה
כְּתוּבָּה
ktuba
ketubah, the (written) marriage contract
קְטוּלָה
כְּתוֹבֶת
ktovet
an address
④ The abstract
כְּתִיב
ktiv
spelling, orthography
Decode it yourself
Strip the prefixes, suffixes and vowels. Three consonants remain, and the meaning lives there.