ἁπαλὸς [2 verses] (adj sg masc nom) "Tender" is hapalos, which means "soft to the touch," "tender," and "delicate."  - The word translated as "tender" also means "soft to the touch," and "delicate." This section of verses generally contrasts the hard, cold, and dark with the soft, warm, and light.

ἁπάντων. [4 verses]](adj pl neut gen) "Of all" is from hapas, which means "quite all," "the whole," "all together," "all possible," "absolute," "every one," "everything," "every," "in any cause whatever," "in every matter," and (as an adverb) "altogether."  It is the common word for "all," -pas, preceded by a prefix ha- that means "the same,"  -- The term translated as "of all" includes several senses of "everything," "all possible," and "everything." Jesus only uses it four times,

ἁπλοῦς  [2 verses] (adj sg masc nom) "Single" is from haplous, which, as an adjective, it means "twofold", "single", "simple", "plain", "straightforward", "simple", "open", "frank", "simple-minded", "unalloyed[metals]," and "pure[metal]. - - - The Greek word translated as "single" primarily means "single," but it also means "open," which applies to eyes, but it means "open" more in the sense of being "frank" from its meaning as "straightforward." The sense here of that could be "seeing straight."  The "single" could also mean "focused" when applied to eyes. 

ἅψας [3 verses] (part sg aor act masc nom) "When he has lighted" is hapto, which means to " fasten or bind to", "join", metaph. "engage in", "undertake", "begin", "set to work", "lay hands on",  "touch", "affect",  "grasp with the senses", "perceive", "have intercourse with a woman", "come up to", "reach", "overtake", "make use of", "avail oneself of", "kindle", and "set on fire". - The Greek verb translated as  "when he has lighted" means primarily "to join" or "touch"and "set to work," with a lot of the same special uses as "join" in English.  However, it also means "to kindle," and "set on fire." It is unrelated to the word "light." Jesus uses it three times, all in Luke, to mean "to light."

ἅπτου, [4 verses](verb 2nd sg pres imperat mp) "Touched" is from haptomai, which means to "fasten to," "to adhere to," "to cling to," "to have intercourse with a woman," "to touch" and "to assail." -- The word used for "touch" means to "fasten to," "to adhere to," "to cling to," "to have intercourse with a woman," "to touch" and "to assail." It has the sense of "adhere to" and "grasp" in the middle voice rather than simply touch. When it is in the middle voice it has a genitive object.  The sense of "ascend" has an idea of ascending to a higher state of knowledge.