The noun τειχος (teichon) means wall and specifically a city wall or more generally a city's defensive ramparts (hence the plural in Hebrews 11:30). It appears that Greek city walls were named in a time when rough mounts of mud sufficed, as our noun stems from the Proto-Indo-European root "deyg-", to knead or form, from which English gets words like dough and dairy but also fiction, figure and figment (via the Latin noun figura, form, and verb fingo, to form).

Our noun τειχος (teichon), city wall, is used 9 times in the New Testament; see full concordance.

Obviously closely related to the above, the noun τοιχος (toichos) also means wall, but rather the wall of a house or enclosure (or the side of a tent, ship, a human body, a bathtub, and so on). This noun occurs in Acts 23:3 only, in the curious term of abuse "you whitewashed wall!" In this particular case, our noun τοιχος (toichos) appears to emphasize the synthetic nature of some partition: something deliberately fashioned and placed around some arbitrary area, feigning importance but empty inside. From this noun comes:

The verb θιγγανω (thiggano) means to lay hands on so as to form or influence (with or without any specific intent). This verb stems from the same PIE root as the above, and in the classics it expresses a broad range of nuances: from embracing and having intercourse, to attack and manhandling someone. Our verb may describe the reaching of some objective, a touching upon some topic in conversation, or the apprehension of some topic in the mind.

Our verb occurs in Colossians 2:21, and Hebrews 11:28 and 12:20 only; the latter reference speaks of an animal stepping onto God's holy mountain, and simply by being an animal, changing the natural order of things according to its own inclinations and pursuits.