Formerly「pursue, follow after」that is comprised of「erection with emphasis」(as in the left element of 'returning home' 帰) paired with「concubine, sitting person, service provider」to mean FLAMING IN HEAT, HEATED. Other possible element combinations are「male person」with「emissions」and「taut erections juxtaposed with emissions」(see 暑 for these details).「Erection in pursuit of service provider」does describe a HEATED, FLAMING condition, as do the elements as「emphasis markers with taut erection(s).」An analogy is being depicted between a burning stick with a red ember at one end, the start of building a fire after rubbing and twisting the stick between two hands, and a「human male's taut erection with emissions upward.」…there simply were not too many Zippo® lighters around, nor books of safety matches in the old days. Fires were started by holding a stick erect against another piece of flat wood and screwing it between two hands (later with a bowstring 弓), or rubbing the tip hard against a groove in another piece of wood until a red ember formed at the end due to friction. Clearly, hard rubbing the tip of a woody shaft against a groove provides another similar analogy of a HEATED, FLAMING condition.
　In English also, references to being 'in heat,' 'light my fire,' 'burning lust,' and so on suggest something is BURNING, igniting passion, flaming, or some say love. Be sure to see another glyph meaning in Chinese「to catch fire, on fire burning, flaming」(着) using the elements 'eyeing sheep' with an 'erection.'
　From time immemorial, that familiar burning desire, the hot hot hot in one's loincloth, the feeling that 'somethin's burning deep inside, and I think it's love' has been with bonobo-humans. Some have suggested that FLAMES, and FIRE is something that only「people」have learned to use and「emit」yet people do not normally emit fire or flame; spontaneous human combustion is extremely implausible.
　However, what does「spurt up from male persons」normally are emissions of ejaculate (人, 丷), and so the elements as male person emitting upwards still might apply to HEATED, BURNING, on FIRE and FLAMING lust or passion. See also the glyph meaning 'burning, calories' (卡) that uses the elements of 'raising flaccid, or, lower parts of a divine young female' with all its meanings (that is, a female human, or, a female ewe sheep: see 着).
　As a classifier for military units in dynastic China, and as Tuesday in Japan, note that the ancient Germanic god of war and flying sky high (Tiu) is also the namesake of the third day of the week in English: Tuesday…all meanings associated with FLAMING HOT HEATED.

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: fire; urgent; ammunition; fiery or flaming; internal heat (Chinese medicine); hot (popular); classifier for military units (old)
Japanese: Tuesday, fire, flame, blaze, an iron, apron of a gun, cover for the touch-hole on a cannon or matchlock, protection against fire, burning at the stake, burning to death, to catch fire, to provoke, to catch fire from, to be ignited, traditional Japanese fire extinguisher, body covered with flames, lighting a torch, lighting up a lamp, person who leads a funeral procession with a torch, fire tongs, a blister
Unihan extended: fire, flame; burn; anger, rage
EDRDG: fire