voice; speech; phone (as opposed to a phoneme); speech sound; audio; sound (as opposed to the picture)
receiving (a message, letter, email, etc.); reception (radio, TV, etc.)
interval; period of time; among; between; good opportunity; chance
security; guarantee; collateral; guarantee (e.g. of safety)
to leak (urine, feces); to soil one's pants; to dump (untreated waste, sewage, etc.); to discharge (untreated effluent); to leak (information, secrets, etc.); to bleed (a deficit, losses, etc.)
to worry (about); to be concerned (about); to have trouble doing ...; to struggle to ...
friendly army; friendly troops; allied army
space; air; midair; (from) memory; (by) heart
drawing; picture; diagram; sight; scene
to be placed on; to be set on; to be piled on; to appear (in print); to be mentioned; to be recorded
warships and other vessels; naval vessels
beginning; opening; start; outset
addition; annexation; appendage
to fix; to settle; to standardize; constant; definite; uniform
one by one; each; every; at intervals of
(one's) current position; current location; present position
location information (as used by location-based services, e.g. GPS position)
absolutely essential; indispensable; vital; critical
obstacle; impediment; disability; handicap; steeplechase; obstacle race
occurrence; incidence; generation (of power, heat, etc.); production; ontogeny; development
reflection (of light); reflection (of society, attitudes, etc.); application (of an update, changes, etc.); taking effect
official; formal; formula (e.g. mathematical); official (social media) account (of a company, organization, etc.)
another thing; other things; another man's property
to hang; to suspend; to lower; to reduce; to demote; to move back
duplication; repetition; overlapping; redundancy; restoration
normal; usual; ordinary; everyday
blank space (in a document); blank; void; whitespace
to escape (disaster, death, etc.); to be saved from; to be rescued from; to avoid (e.g. punishment); to evade (e.g. responsibility); to avert
brush tip; first on a list; head; chief
condition; assumption; intention; intent; premise
measure; step; countermeasure; counterplan; countermove; strategy
difficult to ... (physically or emotionally); hard to ...
serious; important; significant; grave; weighty
defect; fault; flaw; deformity; deficiency; shortage
program (of events, music, etc.); programme; program (booklet); brochure; (computer) program; programming
to go through formalities
presence (e.g. of an observer); observation; trading session (at an exchange); rising from a crouch to charge; initial charge
engineer; technical officer