secret, private, surreptitious

secret, secrecy, confidentiality...

close (relationship, connection, etc.)...

smuggling, contraband trade

density

illicit sale, smuggling, bootlegging...

strict, close, precise...

intimacy, friendship

precise, exact, detailed...

crowding together, clustering together, close formation...

smuggling oneself into a country, illegal immigration

rigour, rigor, closeness...

locked room, secret room

smuggling (people), stowing away

close adhesion, sticking firmly (to), being glued (to)...

poaching

close thicket, dense forest, jungle...

secret agreement

overcrowding, congestion, overpopulation...

secrecy, highly classified information

minute, detailed, careful...

esoteric Buddhism, Tantric Buddhism, Vajrayana...

shutting tightly, making airtight, sealing hermetically

private funeral, secret burial

fine (grain, workmanship, etc.)...

secret, clandestine, covert...

dense, thick, rich (flavour...

dense, thick, crowded...

anonymous report, (secret) information, tip-off...

poaching (fish or seafood)