pat
n.
c.1400, "a blow, stroke," perhaps originally imitative of the sound of patting. Meaning "light tap with hand" is from c.1804. Sense of "that which is formed by patting" (as in pat of butter) is 1754, probably from the verb. Pat on the back in the figurative sense attested by 1804.
adv.
"aptly, suitably, at the right time," 1570s, perhaps from pat (adj.) in sense of "that which hits the mark," a special use from pat, n. in sense of "a hitting" of the mark. The modern adjective is 1630s, from the adverb.
v.
1560s, "to hit, throw;" meaning "to tap or strike lightly" is from 1714; from pat, n.. Related: Patted; patting. The nursery rhyme phrase pat-a-cake is known from 1823. Alternative patty-cake (usually American English) is attested from 1794 (in "Mother Goose's Melody, or Sonnets for the Cradle," Worcester, Mass.).
☞ pat, pass, path
词根：pat = to walk
词根pat来自拉丁语的词根pat 意为to walk。同义词根有来自拉丁语的ambul[ambl]。
同源词：
1. expatiate [向外走出去ex(=out) + pat(=walk)]
vi.详述，细说
She expatiated on the topic of flower arranging.她就插花这一主题进行了详细的阐述。
2. peripatetic adj.流动的；巡回工作的 peri(=around)
peripatetic religious teachers of India 印度的周游四方宗教教师
词根：pat = walk （走）
peripatetic 巡回 走动的（peri来回+pat+etic）