sighing — to let out one's breath audibly, as from sorrow, weariness, or relief.
spying — a person employed by a government to obtain secret information or intelligence about another, usually hostile, country, especially with reference to military or naval affairs.
trying — extremely annoying, difficult, or the like; straining one's patience and goodwill to the limit: a trying day; a trying experience.
defying — to challenge the power of; resist boldly or openly: to defy parental authority.
denying — to state that (something declared or believed to be true) is not true: to deny an accusation.
implying — to indicate or suggest without being explicitly stated: His words implied a lack of faith.
relying — to depend confidently; put trust in (usually followed by on or upon): You can rely on her work.
supplying — to furnish or provide (a person, establishment, place, etc.) with what is lacking or requisite: to supply someone clothing; to supply a community with electricity.
underlying — lying or situated beneath, as a substratum.
Four-or-more syllable rhymes
instrument flying — the control and navigation of an aircraft by reference to its gauges, with no or only limited visual reference outside the cockpit.