| Main Entry: | |
| Part of Speech: | adjective |
| Definition: | dense |
| Synonyms: | bulletproof, close, compact, firm, hard, hermetic, impassable, impermeable, impervious, inviolable, solid, substantial, thick, unpiercable |
| Antonyms: | clear, penetrable, permeable, porous, soft, thin |
| Main Entry: | adamant |
| Part of Speech: | adjective |
| Definition: | hard like rock |
| Synonyms: | adamantine, flinty, impenetrable, indestructible, rock-hard, tough, unbreakable |
| Antonyms: | flexible, soft, supple |
| Main Entry: | airtight |
| Part of Speech: | adjective |
| Definition: | sealed |
| Synonyms: | closed, impenetrable, impermeable, shut |
| Antonyms: | loose, open, penetrable, permeable, unclosed, unsealed |
| Main Entry: | arcane |
| Part of Speech: | adjective |
| Definition: | hidden, secret |
| Synonyms: | cabalistic, esoteric, impenetrable, mysterious, mystic, occult, recondite, unaccountable, unknowable |
| Antonyms: | common, commonplace, known, normal, outward |
| Main Entry: | close |
| Part of Speech: | adjective |
| Definition: | dense, cramped |
| Synonyms: | circumscribed, close-grained, compact, confined, confining, congested, consolidated, cropped, crowded, firm, impenetrable, impermeable, jam-packed, narrow, packed, restricted, short, solid, substantial, thick, tight |
| Antonyms: | loose, open, uncramped |
| Main Entry: | compact |
| Part of Speech: | adjective |
| Definition: | condensed |
| Synonyms: | appressed, bunched, close, compressed, crowded, dense, firm, hard, impenetrable, impermeable, packed, pressed, solid, thick, tight |
| Notes: | a compact is a formal agreement on rights and conduct, a treaty is a compact between nations, and a contract is a compact between two business entities |
| Antonyms: | loose, slack, uncondensed |
| Main Entry: | complex |
| Part of Speech: | adjective |
| Definition: | difficult to understand |
| Synonyms: | Byzantine, Daedalean, Gordian, abstruse, bewildering, circuitous, complicated, confused, convoluted, crabbed, cryptic, discursive, disordered, disturbing, enigmatic, entangled, excursive, hidden, impenetrable, inscrutable, interwoven, intricate, involved, jumbled, knotted, knotty, labyrinthine, mazy, meandering, mingled, mixed, muddled, obscure, paradoxical, perplexing, puzzling, rambling, recondite, round-about, sinuous, snarled, sophisticated, tangled, tortuous, undecipherable, unfathomable, winding |
| Notes: | something complex may be well-organized and logically constructed as well as subtle and intricate, while a thing that is complicated will have something irregular, perverse, asymmetrical in addition to fundamental intricacy; complex is more formal and technical (a problem in mathematics is complex) while something like personal life can be complicated |
| Antonyms: | apparent, clear, direct, discernible, easy, evident, obvious, plain |
| Main Entry: | convoluted |
| Part of Speech: | adjective |
| Definition: | complicated |
| Synonyms: | baffling, complex, confused, elaborate, impenetrable, intricate, involved, labyrinthine, perplexing, puzzling, serpentine, tangled, tortuous |
| Antonyms: | simple, straightforward |
| Main Entry: | dense |
| Part of Speech: | adjective |
| Definition: | compressed, thick |
| Synonyms: | close, close-knit, compact, condensed, crammed, crowded, heaped, heavy, impenetrable, jam-packed, jammed, massed, opaque, packed, packed like sardines, piled, solid, substantial, thickset |
| Antonyms: | open, scattered, sparse, thin, uncompressed |