τέκνον, [25 verses](noun sg neut nom/acc) "Child" is teknon (techion), which means "that which is born," "child," and "the young." -- The word translated as "son" means "child" but in the most general sense of "offspring." Jesus uses it to refer to older children of a working age. See this article more about these words for "child."

τελειοῦμαι. [5 verses](verb 1st sg pres ind mp contr) "Perfect" is  teleioo, which is a verb that means "to make perfect", "to complete", "to bring to consummation," and "to bring fruit to maturity." - - As a verb, it means "to make perfect", "to make complete", "make perfect", "to bring to consummation," and "to bring fruit to maturity." It would be in the form where the subject acts on themselves, "you might make yourself perfect."

τέλειός [2 verses](adj sg masc nom ) "Perfect" is teleios, which means as an adjective "perfect", "entire", "without spot or blemish", "of full tally or number", "fully constituted", "valid", "full-grown [of animals]", "accomplished [of persons], "perfect in his kind," "absolute", "final [of judgment]", "fulfilled [of prayers]," "having power to fulfill prayer [of gods]", "all-powerful", "full point," and as an adverb "finally", "absolutely", "with full authority", "absolutely", "thoroughly," and "completely." Jesus only uses it twice, and it has a lot of different meanings depending on to what it is being applied. When applied to people, it means either "accomplished," or "the best of a kind." It could also mean "without spot or blemish," but that meaning is usually applied to sacrifices. It could also mean "complete" but that meaning is usually applied to numbers. It means something completely different when applied to God.

Τετέλεσται,  [5 verses] ( verb 3rd sg perf ind mp ) "It is finished" is  teleo, which means "to complete", "to fulfill," and "to accomplish." It also means "to bring to perfection", "to pay what one owes," and "to execute a legal document."  -- "Finished" is translated from a Greek word, which means "to complete" and "to accomplish," especially in the sense of having goal.  It also means "to bring to perfection." The form is the third-person, passive, past perfect, so "it has been accomplished."

τελεσφοροῦσιν [1 verse](verb 3rd pl pres ind act) "Bring fruit to perfection" is from telesphoreo, which means "bring fruit to perfection," of young women, "bear perfect offspring," generally, "bring to a head," and, in the passive,  "to be brought to perfection."  -- The verb translated as "bring fruit to perfection" means "to ripen fruit," of women, "to bear perfect offspring," and "to dring to a head."