H. P. Grice quotes from Lewis and Short, "significatio," but goes for "significo"

signĭfĭcātĭo , ōnis, f. id..

I. A pointing out, indicating, denoting, signifying; an expression, indication, mark, sign, token, = indicium, signum, ἐπισημασία, etc. (freq. and class.).

(α). Absol.: “gestus sententiam non demonstratione sed significatione declarans,” Cic. de Or. 3, 59, 220: “aliquem nutu significationeque appellare,” id. Fam. 1, 9, 20: ignibus significatione factā. Caes. B. G. 2, 33: “significatione per castella fumo factā,” id. B. C. 3, 65; id. B. G. 7, 81.—With subj. gen.: “ex significatione Gallorum,” Caes. B. G. 7, 12 fin.: “litterarum,” Cic. Imp. Pomp. 3, 7.—

(β). With obj. gen. (so most freq.): “voluntatis,” Cic. Clu. 11, 31: “victoriae,” Caes. B. G. 5, 53: “adventus,” id. ib. 6, 29 fin.: “virtutis,” Cic. Lael. 14, 48; cf. id. Off. 1, 15, 46: “significatio calamitatum,” id. Div. 2, 25, 54: “artificii,” id. de Or. 2, 30, 153: “probitatis,” id. Lael. 9, 32; id. Fam. 5, 7, 2 et saep.—Plur.: “valetudinis significationes,” Cic. Div. 2, 69, 142: “rerum futurarum,” id. N. D. 2, 66, 166. —

(γ). With object-clause (very rare): “ex quibus magna significatio fit, non adesse constantiam,” Cic. Off. 1, 36, 131.—Plur.: “multas nec dubias significationes saepe jecit: ne reliquis quidem se parsurum senatoribus,” Suet. Ner. 37.—

II. In partic.

A. Pregn., like the Gr. ἐπισημασία, a sign or token of assent, an expression of approbation, applause: “populi judiciis atque omni significatione florere,” Cic. Sest. 49, 105; cf. id. ib. 57, 122; “59, 127: ut ex ipsā significatione potuit cognosci,” Caes. B. C. 1, 86.— Plur., Cic. Q. Fr. 1, 1, 14, § 42: “significationibus acclamationibus multitudinis,” Liv. 31, 15, 2 (corresp. to assentatio).—

B. Also, like ἐπισημασία, a sign, token, foretoken, prognostic of the weather (Plinian): “est et aquarum significatio, etc.... caeli quidem murmur non dubiam habet significationem. Praesagiunt et animalia,” Plin. 18, 35, 85, § 359 sq.—

C. In rhet. lang., significance, emphasis: “significatio est, quae plus in suspicione relinquit, quam positum est in oratione,” Auct. Her. 4, 53, 67; Cic. de Or. 3, 53, 203; id. Or. 40, 139; Quint. 9, 2, 3 (as a transl. of the Gr. ἔμφασις).—

D. In gram., meaning, sense, import, signification of a word or phrase: “verbi,” Varr. L. L. 9, § 40 Müll.: “scripti,” Cic. Part. Or. 31, 108; cf. id. ib. 38, 132: “est igitur tropus sermo a naturali et principali significatione translatus ad aliam,” Quint. 9, 1, 4: “ejusdem verbi contraria significatio,” id. 9, 3, 68: “voces eaedem diversā in significatione ponuntur,” id. 9, 3, 69: “verborum,” id. 10, 1, 10: “latens,” id. 10, 1, 90: “propriae,” Gell. 12, 13, 2.—So the titles of the lexical works of Aelius Gallus, Verrius Flaccus, Festus, etc.: De verborum Significatione or Significationibus.—

E. Meaning, intent: “duas significationes habet propositio vestra,” includes two assertions, Sen. Ep. 87, 28.