An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A criterion for the instability of a basic swirling flow with an arbitrary dependence of angular velocity Ω(r) on the distance r from the axis of rotation. This states that in → inviscid fluids: Ω(r) < 0 for instability, where Ω = (1/r³) (d/dr)(r⁴Ω⁴).

→ Rayleigh; → criterion.

The forces of jets from a comet's nucleus that can cause a rocket-like effect and alter a comet's direction of motion slightly.

→ non-; → gravitational; → force.

A dark lane that appears behind the coma in some comets. It is not the shadow of the true nucleus but sometimes may be a region of the near-tail that lies behind the densest part of the inner coma and therefore receives less sunlight.

→ shadow; → nucleus.

A → trans-Neptunian object located in the → Kuiper belt, nicknamed Ultima Thule. It is elongated in shape with estimated dimensions of about 31 by 19 km. NASA's → New Horizons spacecraft conducted a close → flyby of the object on January 1, 2019 just 3,500 km above the object's surface. The images it took show that the object has in fact two distinct lobes. At a heliocentric distance of 44 → astronomical units, (486958) 2014 MU₆₉ is the most distant object ever visited by a spacecraft. It has an → orbital period of 298 years, a small → inclination (~ 2.45°), and a low → eccentricity (0.042).

→ asteroid designation.

Suffix forming adjectives with meanings "capable of, susceptible of, worthy of, tending to."

M.E., from O.Fr., from L. -abilis, -ibilis, from -a- and -i- + -bilis.

The capability suffix -i is added to the infinitive form.
-pazir "receiving, accepting, admitting, having," from paziroftan "to receive, accept, admit," Mid.Pers. padiriftan, padir- "to receive, accept," from Proto-Iranian *pati- + *grab- "to grab, seize, take," Av./O.Pers. grab- "to take, seize;" cp. Skt. grah-, grabh- "to seize, take," graha "seizing, holding, perceiving," M.L.G. grabben "to grab," from P.Gmc. *grab (E. grab); PIE *ghrebh- "to seize."

A prefix with several meanings: "characterized by," "of the nature of," "belonging to or connected with a division of animals characterized by or of the nature of," "belonging to or connected with a family of plants of the nature of."

From L. -aceus.

-âsâ a suffix denoting "resemblance; nature; relation," from Mid.Pers. suffix -ihâ forming adverbs.

1) Adjective suffix denoting "of, relating to, or characterized by;" e.g. astronomical, material, equal, final, general, directional, fictional, etc. Variant → -ar.
2) Noun suffix, used with verbs (refusal, rehearsal, etc.) or nouns (canal, etc.).

1) M.E., from O.Fr., from L. -alis
2) M.E. -aille, from O.Fr., from L. -alia, from neuter pl. of -alis.

1) -i, contraction of -ik, → -ic; -var Mid.Pers. -uwar, -war, from O.Pers. -bara, from bar- "to bear, carry," variant -ur; -mand from Mid.Pers. -omand, O.Pers./Av. -mant, cf. Skt. -mant.
2) In Persian, -âl, a suffix of attributes and similarity, is used to form adjectives that often become nouns. Sometimes it occurs as -al or -el and may be confounded with -ul and -ulé, → -ule. Its link with L. -alis is not established. Some examples:
dombâl "rear part; continuation; tail," from domb "tail" + -âl,
cangâl "fork; claws," from cang "claw; hook" + -âl,
pušâl "tinder, rubbish," from puc, puk "hollow" + -âl,
ravâl "trend," from row present stem of raftan "to go" + -âl,
xoškâl "dried twigs and leaves of a green tree," from xošk "dry" + -âl,
tofâl "remains of anything squeezed," from tof "saliva" + -âl,
kupâl "club," from kup-, kub(idan) "to beat, strike, pound" + -âl,
gowdâl "hole, pit, low place," from gowd "deep" + -âl,
tâval "blister," from tâv-, tâb-, tâbidan "to become warm, burn," + -al.
kandâl "pit (Qâeni), watercourse, canal (Kordi)," from kand stem of kandan "to dig, pluck, extract" + -âl,
mərdâl (Tâleši Xošabar) "dead," from mərd "to die" + -âl,
capâl "left-handed," from cap "left" + -âl,
gaštal (Laki) "wanderer, vagabond," from gaštan "to turn, return, change, look about" + -al,
kašal (Torbat Heydariye-yi) "elongated," from kašidan "to draw, extend" + -al,
gerdel (Hamadâni, Lori, Qomi) "round, loop," from gerd "round" + -el,
peškel "orbicular dung of sheep," from pešk "dung" + -el.

Suffix used to form nouns either from adjectives or from verbs; it expresses 1) state or condition (brilliance, absorptance); 2) action (e.g. continuance).

M.E., from O.Fr., from L. -antia.

-Egi, -igi, -âi, -âyi, -eš Pers. noun suffixes denoting state, condition.

Same as → -ent.

A suffix of adjectives, meaning "of, relating to, or resembling," as in polar "of or relating to": molecular, "being": spectacular.

M.E., from O.Fr. -er, from L. -aris, variant of -alis, → -al.

An adjective and noun suffix denoting thing or person belonging to or connected with.

From L. -arius, -aria, -arium "connected with, pertaining to; the man engaged in."

-i, Mid.Pers. -ig, -ik, → -ics.

1) A suffix used in chemical terminology, in particular to indicate a salt of an acid ending in -ic and not beginning with → hydro-, such as silicate, nitrate, sulfate.
2) Verbal suffix denoting "to act upon" (in a specific way), "to cause to become."

1) From M.E. -aten, from L. -atus p.p. ending of 1st conjugable verbs.
2) Very likely from N.L. expressions as plumbum acetatum salt produced by the action of acetic acid on lead.

A suffix meaning "killer; act of killing." → genocide.

M.E., from L. -cida "cutter, killer," -cidium "act of killing," from combining form -cidere, from caedere "to strike down, kill."

-koši, from koštan "to kill," Mid.Pers. kuštan "to kill, to stuggle;" related to košti "fighting, wrestling;" Av. kuš- "to fight, to struggle" (Cheung 2007).

A combining form occurring in loanwords from Greek with the meaning "rule, government, governing body." → theocracy.

From Fr. -cratie, from M.L. -cratia, from Gk. -kratia "power, might; rule; authority," from kratos "strength," from PIE *kre-tes- "power, strength," suffixed form of root *kar-/*ker- "→ hard." "hard."

From sâlâr "leader, chieftain, commander;" Mid.Pers. sâlâr "leader, master;" variant of sardâr "commander, chief, general," from sar "chief, → head," + dâr "having, possessor," from dâštan "to have, to possess," Mid.Pers. dâštan; O.Pers./Av. root dar- "to hold, keep back, maintain, keep in mind;" Skt. dhr-, dharma- "law;" Gk. thronos "elevated seat, throne;" L. firmus "firm, stable;" Lith. daryti "to make;" PIE *dher- "to hold, support."

A noun suffix equivalent to → -ance.

→ -ance.

A suffix denoting quality or state.

From L. -entia.

A suffix with the sense "causing or performing an action or existing in a certain condition." Same as → -ant.

From Fr. -ent and directly from L. -entem (nominative -ens), pr.p. suffix of verbs in -ere/-ire.

An adjective forming suffix with the meanings "ccomposed of, resembling, having the nature of."

→ -ous.

A suffix serving as the regular English formative of agent nouns, being attached to verbs of any origin.

M.E. -er(e), corresponding to L. → -or, O.E. -ere; cf. Ger. -er, Sw. -are, Dan. -ere.

→ -or.

A suffix denoting "action, process, state, or condition," and corresponding to adjectives ending in -escent. → luminescence.

From L. -escentia, from escens, from esse "to be," → existence, + -ia

-esti, noun from -est, variant of ast, hast "is, → exists," cognate with L. -escence, as above.