Related by context. Frequent words. (Click for all words.) 55 impenetrable 54 porous 46 penetrate 45 invulnerable 43 impervious 43 penetrated 43 impregnable 42 penetrating 42 permeable 41 soft underbelly 41 fortified 40 dense 40 penetrates 40 impermeable 39 militarized 39 Achilles heel 39 invisible 39 malleable 39 opaque 39 homogeneous 38 problematic 38 brittle 38 exploitable 38 unreadable 37 degraded 37 rudimentary 37 amorphous 37 uninviting 37 pliable 37 adaptable 37 vulnerable 36 problematical 36 indistinguishable 36 ineffective 36 widely dispersed 36 imbedded 36 reductive 36 flimsy 36 defensible 36 usable 36 sieve 36 homogenous 35 impotent 35 monolithic 35 compartmentalized 35 useless 35 paradoxically 35 multilayered 35 camouflaged 35 unusable 35 ossified 35 exposed 35 susceptible 35 hardened 35 primitive 35 Achilles Heel 34 nonfunctional 34 visible 34 testable 34 detectable 34 circumscribed 34 feeble 34 hermetically sealed 34 pervasively 34 confining 34 fortress 34 thin skinned 34 resistant 34 soluble 34 inhospitable 34 ineffectual 34 unforgiving 34 vegetated 34 translucent 34 perimeter 34 glaringly obvious 34 resilient 34 oxidizing 33 unappealing 33 adept 33 mesh 33 inedible 33 serviceable 33 exploited 33 rendered ineffective 33 weakest link 33 insecure 33 sophisticated 33 clumsy 33 plausible 33 blurry 33 readable 33 inaccessible 33 fragmented 33 superfluous 33 indigestible 33 infeasible 33 indestructible 33 unattractive 33 neutralized 33 fortifications