tran·sit / ˈtranzit/ • n. 1. the carrying of people, goods, or materials from one place to another: a painting was damaged in transit. ∎  an act of passing through or across a place: the first west-to-east transit of the Northwest Passage | [as adj.] a transit airline passenger. ∎  the conveyance of passengers on public transportation. ∎  Astron. the passage of an inferior planet across the face of the sun, or of a moon or its shadow across the face of a planet. ∎  Astron. the apparent passage of a celestial body across the meridian of a place. ∎  Astrol. the passage of a celestial body through a specified sign, house, or area of a chart. 2. inf. (in full transit theodolite) a tool used by surveyors to measure horizontal angles.• v. (-sit·ed, -sit·ing) [tr.] pass across or through (an area): the new large ships will be too big to transit the Panama Canal. ∎  Astron. (of a planet or other celestial body) pass across (a meridian or the face of another body). ∎  Astrol. (of a celestial body) pass across (a specified sign, house, or area of a chart).

tran·si·tion / tranˈzishən; -ˈsishən/ • n. the process or a period of changing from one state or condition to another: students in transition from one program to another| a transition to multiparty democracy. ∎  a passage in a piece of writing that smoothly connects two topics or sections to each other. ∎  Mus. a momentary modulation from one key to another. ∎  Physics a change of an atom, nucleus, electron, etc., from one quantum state to another, with emission or absorption of radiation.• v. undergo or cause to undergo a process or period of transition: [tr.] the network ought to be built by the federal government and then transitioned into private industry [intr.] we have transitioned from a high-intensity combat operation to a support role in the community. DERIVATIVES: tran·si·tion·al / -shənl/ adj.tran·si·tion·a·ry / -ˌnerē/ adj.

transition In genetics, a type of mutation (a nucleotide-pair substitution) that involves the replacement in DNA or RNA of one purine with another, or of one pyrimidine with another. An example is the change of GC (guanine-cytosine) to AT (adenine-thymine).

transition In genetics, a type of mutation (a nucleotide-pair substitution) that involves the replacement in DNA or RNA of one purine with another, or of one pyrimidine with another. An example is the change of GC (guanine–cytosine) to AT (adenine–thymine).

transition The substitution of a purine base containing nucleotide for another with a purine base, or a pyrimidine base containing nucleotide for another with a pyrimidine base. Transitions generally occur more frequently in evolution than transversions.