istya noun "knowledge" (IS). Also ista (#1).
Quenya
istare
noun. knowledge
ista
knowledge
istya
knowledge
issë
knowledge, lore
issë noun "knowledge, lore" (LT2:339; rather ista or istya in Tolkien's later Quenya)
handë
knowledge, understanding, intelligence
handë noun "knowledge, understanding, intelligence" (KHAN). Note: *handë is (probably) also the past tense of the verb har- "sit".
Nolmë
knowledge, philosophy (including science)
Nolmë ("ñ")noun "knowledge, Philosophy (including Science)" (PM:360 cf. 344)
ista (1) noun "knowledge" (IS). Also istya.